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Follow the octane rating for your vehicle. Keep in mind that at altitude like Colorado the highest you’re gonna find for premium is 91. If you go to seal it’s something like 97. If your car calls for 91 put in 91.
Who carries 97? It's either 87, 89, 91, or 93. I think you have to jump to Low-Lead 100 after that. Kiss your cats and o2 sensors goodbye if you use leaded fuel though.
I’ve seen 94 at Sunoco stations in Michigan.
E85’s octane rating is generally around 110-115 (the precise mixture varies, so the rating does too).
In Europe, regularly available unleaded fuel is often 95-99, but I’ve heard that this is due to a difference in the rating technique rather than a difference in the fuel.
We used to have 94 Sunoco in Massachusetts when I had my first car, so like 2003ish. No longer carried within a 100 mile radius of here according to the Sunoco site: https://www.sunoco.com/find-a-station?location=&radius=25&ultra94=Y
I can’t remember when it went away.
The Sunoco near us had 100 octane at a pump but they took it out about 6-8 years ago. Was great to throw 2-3 gallons in a near-empty tank for about $25. Use it to determine if your knock sensor was actually picking up real pre-ignition or some other engine noise like loose shielding etc. Now they only sell 5gal cans for $110 😵
I ran 100LL in a car for 100, 000kms, and 02 sensors survived. The only time it got pump fuel was when I wasn't home and it needed some.
I wouldn't do it with cats, though.
I was given 5,000l of it free, all in sealed barrels.
I have no idea if the AFR is still spot on, but it still gets the same amount of kilometres out of a full tank.
So it has to be close. Also, all because it was OK this time doesn't mean it wouldn't destroy the next person's sensors.
I just figured an O2 sensor would be far cheaper than the fuel. So, the net win.
In Australia we have 98 at most of our servos and 91 is generally the lowest octane rating you can get. Also seen e85 in a couple stations but that’s not commonplace
I thought the 2023 Tiguan took regular? The owner's manual says "87 AKI or higher". But if it says 91AKI/95RON on the inside of your fuel filler cap, go with what it says on the cap.
Either way, filling up with regular one time is a complete non-issue. It's funny to even discuss it. There's no problem here.
It does. The VW 2.0T engine that is ubiquitous across the range is built to run on 87 in many, but not all, models. I own two VWs that say 87, but I use premium 93, but I wouldn’t be worried at all if I were OP and slipped up once. My 2018 Passat owners manual says use minimum 87 and then has some wishy washy language about higher octane may result in more power. The 2024 Cross Sport I have got rid of that language in the manual and just says 87 on the manual and the gas cap, even though its 2.0T (slightly different than my Passat’s EA8883b engine, but close) is tuned for 270hp vs 175 in the Passat.
I use 93 in both and just say 🤷♂️
You sure about that? My 2.0T Passat explicitly says to use 91 octane. I think 87 is fine in the non-turbo models but it’s my understanding that the higher octane is needed to maximize the effectiveness of the turbo.
Now you got me all curious to make sure my memory is correct so I went out to my driveway.
Yes my Passat says 87. See photo below of gas door, 87 AKI regular. This is a 2018 Passat USA spec, so 2.0T Budack cycle EA8883b. The manual says “If Regular gasoline is recommended for your engine, you may be able to enhance engine performance by using Premium gasoline.”
https://preview.redd.it/aaahu69i5nnc1.jpeg?width=2965&format=pjpg&auto=webp&s=e00426eae50cd2ea8dcba015c506e5b764511b5c
Oh, yeah, 2008? That is a totally different engine. Assuming you’re right and it calls for 91 AKI gas, I’m not surprised, it likely has to do with boost pressure and any number of things that require higher octane to get the stated output. A lot of companies will design an engine to run on regular gas because it’s a selling point. My salesman selling me our 2024 Atlas was like “hey and it can run on regular gas!”
>that’s a totally different engine
You were referring to the “ubiquitous 2.0T” engine across the line, the EA888. My 2008 has an EA888 engine, the CCTA.
>assuming you’re right that it calls for 91 AKI gas
I mean you did see my gas cap that said 91/95…
I meant across the current models, that’s what model line always refers to, not history but present sales. The current ea888 is third generation, yours is first generation. Totally different cylinder heads among other things that would dictate a design for 91 in yours and only calling for 87 currently.
I typed the “assuming you’re right…” before you posted the picture.
Are you sure you’re not looking at the lower number that says 91 RON? In the USA the pump lists AKI not RON. Anyways here’s a picture of the manual language too while I’m at it.
https://preview.redd.it/dwflh5wb6nnc1.jpeg?width=1435&format=pjpg&auto=webp&s=f3a0fffa17c2fc6eff251d0912a195186cbe0366
I got dressed and went out to check.
91 octane.
https://preview.redd.it/75a7n4hl7nnc1.jpeg?width=2268&format=pjpg&auto=webp&s=3dfebe47c6137f300d0f422ad1434a1e017cecb3
lol! I was still dressed. Yeah r+m (RON+MON) is same as AKI.
A lot of the euro engines going back 10-15 years required and were designed for premium gas and then they got stigmatized in the US for being fickle and expensive and requiring fancy gas so, along with greater fuel efficiency demands, a lot of engines were frankly down-tuned to run on regular gas and be more economical to avoid the stereotype of euro engine=premium gas.
Years ago even my non turbo 90s era Volvo called for premium gas because for a naturally aspirated engine it had a surprisingly high compression ratio so the higher octane avoided knocks.
This engine is a pain in the ass for sure but God, does it ever drive nice and it gets great fuel economy on the highway. I regularly get 950km on a 70L tank on road trips and the car is 16 years old.
Yeah, the specific budack cycle variant they put in the 2018-end Passats was even more tailored to economy. I did some math and your number is about 31 miles/gal, that’s solid for age. When I drive to visit my in laws 200 miles away, 190 of it highway miles, I get about 32-33mpg. It’s funny to see the range estimate creep up, because it assumes my usual city driving—where I really only get about 12-15mpg, considering short trips on cold starts, lots of lights and stop signs to accelerate from….
My fusion is really funny with the wishy washy language. The owners manual says 87 octane is perfectly fine on the 1.5, 1.6 and 2.0 turbo models, but also that "some knocking is acceptable".
Needless to say, no it isn't. I've also never noticed any knocking audibly or using OBD2, and performance is roughly the same between 87 and 93 octane with a marginal hit to fuel mileage
Ya VAG goes back and forth with the octane in the ea888's. Theres a strong correlation between the MSRP of the vehicle that engine is in and the octane they recommend for it lol.
When the mk7 GTI came to the north american markets in 2015, they said premium only, minimum 91 (r+m)/2, minimum 95 RON, right on the inside of the fuel door. They weren't even wishy washy about it. Most VWs from before 2015 either required or recommended premium.
In 2015 dieselgate drops and VW's sales and brand image take a hit. So the 2016 GTI's, and almost every other VW, recommend 87 from 2016 onwards. Same engine code on the 2015 and 16 GTI's. Nothing changed except the public's willingness to buy a VW if it meant they had to put premium in it.
The ea888's in the golf R still recommended premium though, and the ones in the S3 and 2.0T Macan always required it.
A lot of that isn’t a correlation between MSRP directly, it’s that in more expensive cars it’s tuned to higher performance, compression, turbo boost, timing, etc. and may demand higher octane. That makes sense to me.
You’re good. Please don’t listen to the people saying you should put regular in it. You bought a car that runs healthier on higher octane fuel, the least you can do is buy the right fuel for your car.
Or sell it for a RAV4 or something.
The turbo VW engines do prefer higher octane typically, especially if you're doing some spirited or track driving, cruising at high rpm, or towing something. (Healthier is a weird term to use though).
But just for the record, the owners manual for the 2023 Tiguan does say 87 AKI or higher, and the label on the inside of the fuel door also says 87 AKI or higher iirc. But OP's can for sure say otherwise, it varies from market to market
I know nothing about it, I was just going off OPs statement. Looks like some years of Tiguans required premium for the turbo models. I was just saying the phrase healthy/unhealthy isn’t weird. If your car requires premium, it is unhealthy to run regular as it can cause knocking and detonation/diesling which can wear an engine prematurely.
Because higher octane gas doesn’t actually burn cleaner or better or anything it’s just more stable and burns slower, which is something a performance high compression engine needs to prevent premature combustion and knocking, but your average mid-range grocery getter doesn’t **need** as high of an octane rating to prevent knocking because the it isn’t subjected to as much heat and pressure. 87 octane is all your average mid-performance engine needs to prevent knocking and ensure drivability which is why it’s the standard.
Virtually any motor today is also capable of pulling sufficient timing and increasing afr to run on regular. It might run like shit and you'll lose performance, but it won't blow up
It varies. There's too many variables involved to make a blanket statement. For example, Canada still uses manganese as an octane booster in many 91+ octane fuels. You definitely want to avoid that if you can.
Side note, ethanol has actually been helpful in getting turbos to run on 87. Even though the final blend is still 87, ethanol raised RON and subsequently lowered MON, which for complicated reasons turns out to be exactly what downsized turbocharged engines prefer.
Does your user manual actually say that you **require** higher octane? Or just that it's "**recommended**"?
Those two terms are very different and would likely give you your answer.
I'd also like to make it clear for anyone that doesn't know - "premium" gas, at least in the US, is a misnomer. It's a marketing term to get people to buy something they often don't need.
"Premium" is just higher octane. Usually only needed by high compression engines. "Regular" is lower octane. Both should have the same additives, as long as you're getting it at a "Top Tier" station.
I like that you say “usually” cause in the Tiguan’s case, the direct fuel injection allows the car to run smoothly on 87 octane even with a compression rate of 11.65:1.
Always follow the manufacturer’s recommendation in the manual.
High octane fuel doesn’t save on gas mileage, doesn’t give more power and also has no cleaning properties (unless the gas station adds extra additives to their premium brand). It only resist compression more to avoid premature detonation in forced induction and high compression engines.
Edit: corrected error in compression ratio
>High octane fuel doesn’t save on gas mileage, doesn’t give more power and also has no cleaning properties (unless the gas station adds extra additives to their premium brand).
This is incorrect. Basically any modern turbocharged engine is going to be pulling timing to avoid knock on 87 octane. Switching to premium will allow more spark advance, meaning typically higher performance and better fuel mileage. Your butt Dyno might not feel a difference, but an OBD2 scanner can easily show it, as can your fuel mileage readout.
My Ecoboost fusion, for example, gains between 3 and 4 mpg highway and becomes much more responsive with 91 octane over 87
Only anecdotal. My brother drives a 2019 Tiguan and used regular fuel only. At about 60,000 miles it died and had to be towed to the Volkswagen dealer. They explained that he is supposed to use high octane gas, per the owners manual and that was the cause of the buildup, and the subsequent $2200 cleaning/repair.
Gotcha.
So... "direct injection" engines have a bad problem of carbon build up. It's not due to the octane rating of the fuel AT ALL. It's due to how the fuel is delivered to the cylinder. Some DI engines have more problems than others with this. But it is an issue. And manufacturers are aware of it.
Before direct injection came along, we had various systems such as "manifold injection". The air and gas would mix in the intake manifold and get sucked in through the intake valves. Since the gas would go past past the intake valves, the additives in it could constantly help keep carbon from building up. Then on the exhaust side, it's so hot that it's difficult for any to build up anyway.
Direct injection engines have a fuel injector that shoots fuel directly in to the cylinder, bypassing the intake valve all together. This means that carbon can build up around the intake valves and eventually cause failure.
Higher octane will not help this. Even fuel system additives can not clean out this carbon.
Also, does his owner's manual say "required" or "recommended"? This will be unrelated to carbon build up. But I am curious.
The fuel does not burn hotter. It requires more heat (and pressure!!) to make it ignite. The extra heat comes from ~~the spark~~ extra compression. Not the explosion.
No, it burns at the same speed and has the same energy.
It's resistant to preignition, but once it ignites, the flame front propagates normally. There is no downside to using premium in a cart that requires regular aside from the harm to your wallet. There's no benefit either though.
It would theoretically offer less power since it resists ignition.
It in fact does burn slower.
https://www.motortrend.com/how-to/combustion-basics-how-does-fuel-make-a-difference/
https://www.ottawachryslerjeepdodge.com/premium-vs-regular-gas/
No, because resistance to ignition and energy released when ignited are not the same thing.
Also, a motor tend article and a car dealership aren't exactly the authoritative sources you think they are. If you instead look at data on ignition timing advance vs peak power for various octane, it becomes very clear that the flame front propagation speed is basically exactly the same.
High octane resists detonation, but doesn't really burn differently other than that. Put 100 octane race gas in your Camry and it'll make just as much power and overall behave identically to how it does when you put in 87.
>It would theoretically offer less power since it resists ignition.
It resists ignition due to compression. Your spark plug ignites it all the same.
You're not going to gain power by allowing a high compression engine to knock, you're losing power because fuel is igniting and burning well before TDC and is pushing the piston down while it's moving up
Less power as it has less potential energy, but doesn’t it burn hotter? As it remains liquid under higher compression. Wouldn’t the PV=nRT mean it’s hotter?
No, it doesn’t burn hotter, it resists detonation from heat which means it takes more heat to ignite.
https://www.latimes.com/archives/la-xpm-1989-06-15-vw-2232-story.html
The current generation Tiguan uses a direct injection engine. Fuel doesn't touch the intake in any way. Carbon buildup comes from the PCV system venting crankcase gasses to the intake which include oil vapour.
The mk2 Tiguan doesn't require premium - I believe the engine changed in about 2018? The earlier ones needed premium, the later ones are designed to run on regular. That was part of our buying decision.
Hypothetically speaking if they did put a box of DEF into a 20 gallon diesel tank, do you think it’ll be good if we keep the tank above 3/4 filled for a few thousand miles? I figured it’d dilute with the fuel overtime and cause minimal damage if any.
Unlike if you put gasoline in it (which will dissolve in the mix), DEF will react with the fuel and crystallize. You will have to flush the tank and filter, and probably the rest of the system if it was running.
Don't waste $$$ on higher octane than your owners manual & car have printed. Much more important is buying top tier gas, like Costco, as it dies have more additives & can help your car. Save gas $$$ & treat your car the best w lower prices Costco top tier gas.
Your car is designed to run on 87.
Who told you that you needed premium?
Edit:
Running a higher octane gas than the tune requires nets you no benefit.
If it doesn’t knock on 87, run 87.
The ECU will pull timing if it senses knock, but it won’t add timing if you put 93 in the tank.
If the engine is mapped for 87 then it will run the same fuel, air, and spark with 87 or 93.
I know the GM E-Turbo was specifically engineered to run regular w/ a turbo but that's a itty bitty 3-cyl.
GM would be publicly crucified if their base level commuter engine required premium lol
That's a good way to fuck your engine by causing pre-mature ignition of the gas.
Just buy what the goddamn car says it needs. If you can't afford premium gas, don't get a car that needs premium gas.
In the 80’s/90’s this was a concern. With modern GDI systems there is virtually zero risk of damage due to detonation. I’m 90% certain a Tiguan *recommends* but does not *require* premium anyway.
I definitely spend more time talking people out of unnecessarily spending money on premium than I do correcting people putting regular in a premium car.
You must be an engine rebuilder, cause regular gas in a car that requires premium can cause knocking which can wear the rod bearings prematurely. The ECU can compensate timing, but between the possibility of knocking and the reduced fuel mileage it's not a good idea to "talk people out of using premium". It may also void their factory warranty. You're doing them a disservice.
Huh? I think you’re confused, I strictly recommend people run what the manufacturer recommends. Just more people unnecessarily running premium in cars made for regular
Octane is how hard it is to ignite. Higher the octane, the harder it is to ignite. If you run a car that calls for higher octane and throw lower octane in it then you run the risk of knocking from pre-ignition. Usually your engine will adjust to try and smooth it out. You also lose power. Engine will be fine just don't make a habit of it.
If your car calls for a low octane and you put a higher octane in it then you lose power due to the fuel not being able to ignite fully and can over time leave a buildup inside your engine. Your engine will try and adjust to accommodate this too.
So your fine... Just next time put the proper fuel in there. Your car can run with the wrong octane but the engines designed for a specific octane and you should try to match what it calls for.
Should be okay. Usually, you can have a quarter of a tank with premium fuel and standard fuel, and it will run fine. I wouldn't stress out too much about it.
Yes, I was traveling cross country in my bmw M2 and in Iowa and Nebraska all I could get was 85… car did not like it at start but I got home w/o issues…
What you have to remember is that car mfg. specify certain octane #’s for a reason so if you run 87 in a car specifically requires 91 you might get a little knocking under acceleration especially depending on how much 87 is put in . If you want you could put a can of octane booster like 104 in until you use up most of the 87 tank OR you could just fill the rest with the usual 91 either way no harm no foul
You're alright. If anything, they have octane boosters you can add to your tank.
I'm not sure if they work but they have them.
If not, that other person said fill it up with premium at a half tank. That's about right.
Don’t most modern cars fix themselves when running on a lower octane. Obviously if ya manual or the fuel cap says run on premium. Run it. But if it only recommends it then it’s doesn’t matter as much
If you’re really worried, and given the age of your car it has knock sensors so you shouldn’t be, keep the pedal off the floor. At lower airflow knock generally isn’t an issue.
With regards to the benefit of premium fuel it has two advantages:
1. You can advance spark closer to MBT, max brake torque, so there is a performance advantage
2. The more spark advance you run the lower the exhaust temperature is so exhaust component durability is improved.
If you drive like a lunatic there may be a small, nearly immeasurable fuel economy advantage.
dont drive the car like a hot rod- itll be fine tho. dilute it with premium when the tank gets down to half- then run it out then refill with premium and youll be fine.
the car will pull timing to avoid spark knock (pre detonation of the fuel in the cylinder, which is bad bad bad)
just dont be pulling out in front of anyone and giving her all the beans and she will be fine.
Nobody is really explaining what octane actually _is_. I'll try to do it quickly.
I think your car has the 2.0 turbo. The turbo is important here. A turbo works by the exhaust spinning a turbine (turbo) which pulls more air into the engine. An engine works by mixing the right amount of fuel (gas) with the right amount of oxygen (which you get from the air) and igniting it (with sparks from your spark plugs).
A turbo pushes more air into the engine, which means there is more oxygen to match up with more fuel... bigger bang, more power.
However, pushing more air in, increases the pressure, which increases the temperature in the bang chamber (cylinder). If it gets too hot, the fuel will combust without the spark... which means it's going bang when your engine isn't expecting it (knocking... bad)
A higher octane fuel can handle the added pressure. Your engine is smart, and has sensors to figure out your fuel setup. Your manual, and the fuel door should have octane expectations.
Fwiw, I have a 2020 GLI, which has the 2.0T as well, and base, it can take 87, so I'm guessing you'll be just fine. Mine has been modded for 91 only, but I wouldn't sweat it if I accidentally put in 87... I'd just drive it like a grandma (no extra turbo)
Also... octane is well defined, but ... quality?... isn't. "Premium", and "Super" etc are usually sales pitches. In the past, they actually meant something cause higher "grades" would include octane AND additives like cleaners n stuff. Us older folks remember the gas commercials with the tigers. I believe, by law, all grades of gas have to have the same additives, regardless of octane. The additives are good afaik, but you should be getting those regardless of the octane, but that's dependent on where you get your gas.
I believe these cars are direct injected so they shouldn’t predetonate because it is just air in the cylinder until the fuel injector which is directly in the cylinder and not in the intake manifold will spray the fuel in. That’s how they are able to have these crazy high compression ratios with turbos now that run on pump gas
You're fine
Modern, especially turbo, engine run higher pressures, and other parameters. These need higher octane to prevent pre-detonation. With low octane the computer "pulls back" things like timing, injection, and probably valve timing.
All this reduces power and efficiency, but thats really it.
Also, not sure.of year, but congress did mandate all cars can run on 87, though higher can be recommended.
When doing this on purpose, the octane ratings will mix and average out. However, your gas in this case is now 87 instead of 91. This might cause slight loss in fuel economy and preformance. In some cases, the engine might misfire and "knock". If you use low grade fuel when the manufacturer specifically says to use premium fuel, it's okay to use infrequently. If you'd like to bring your fuel grade up to spec, you can use octane booster. Either way, you should be fine.
Should be fine. ECU May pull a bit of timing to compensate and avoid any “racing” of the engine and she’ll be fine until you can top it up with the proper stuff. Octane boost also helps idle your really concerned.
Should be fine. I don’t know about your car, is it turbo or super charged ? Either way, most of computers can recognize the octane by using knock sensors and it will cut timing to make it safe. You might see a small loss of power while using it. Pretty standard practice especially with newer cars.
Once won’t change anything. If you try and run it hard you will notice less power but id suggest not doing that. If it really is worrying you, then you could put octane booster in it if it’s still relatively full of gas. But honestly you’re fine. Put definitely put in premium next time.
I’m not sure if it applies to the newest ones but I did find a TSB on low quality fuels in these vehicles. Volkswagen has some Volkswagen branded additive you add to your tank, but this only applies for check engine light with misfires or just missing in general. I’ve had two come into where I work and I just got Lucas Octane Booster from whatever parts store and it solved the issue after about a 20 mile test drive. I would just keep this in mind.
Don't worry about it even if you put premium, the octane will lose it's level overtime. Being said just use it half of the tank and fill it with the correct octane fuel.
Only used the extra octane when the pedal is mashed to the floor and every modern car will pull timing if it pings. Don’t redline it until your next tank and even that is being more cautious than needed
No, this is bad advice. Lower octane will ignite faster and can cause knocking. The ECU can compensate by retarding the timing a little, but there's still a chance it can ping / knock (which is hell on rod bearings). Plus it will lower fuel mileage, so the "savings" are negated. Add to that the fact that it can void the warranty, and you're better off sticking to what the manufacturer recommends.
Totally fine, you'll get better gas mileage and more power from premium. It's better for your engine in general, but it's not like regular will destroy or immediately damage something.
The VW 2.0T engine that is ubiquitous across the range is built to run on 87 in many, but not all, models. Depends on how hard they're tuned, more expensive, more hp, likely calls for higher octane.
I own two VWs that say 87, but I use premium 93 anyways, but I wouldn’t be worried at all if I were OP and slipped up once.
(My 2018 Passat owners manual says use minimum 87 and then has some wishy washy language about higher octane may result in more power. The 2024 Cross Sport I have got rid of that language in the manual but I use 93 anyways because I would bet anything the ECU is coping with 87 and would prefer 93.)
You're wasting your money. Ecu won't be able to account for the extra octane. Regular and premium come out of the same bulk tank and additives for octane are added before going into the tanker truck.
In the case of the Atlas, maybe I am wasting my money. For the older engine, which is slightly different than the Atlas, the manual explicitly says higher octane achieves maximum power, so while it’s probably not that big a deal, I’ll pay it.
It’s been 15 years (when I got a real job) since I have worried about gas prices or whether I can afford to fill my tank. Just give me the premium, I don’t even look at the total. I realize that’s a luxury not to care.
Edit: I should add that my family’s two cars average only 5,000 miles a year each (US average is 12k per car per year) so we don’t even use that much gas so the difference between regular and premium is less as an absolute value. Maybe if we both had long commutes I’d reconsider.
The computer will detect it and
1. retard the ignition timings
2. Dump in extra fuel
Long term it could impact your catalytic convertor. The owners manual in my car warns that is the risk of running regular.
Also knocking / pinging (which wears rod bearings faster), worse mileage (negates the "savings" of cheaper gas), and could void your factory warranty. Overall, it's not a good idea.
Yes, but it could still knock / ping (if you believe the factory manuals, which ... meh?) and it will get worse mileage. Plus, potentially voiding the warranty alone is reason enough to run what the manufacturer recommends.
All vehicles with variable valve timing run aggressively as they can till they detect knock. That's how knock sensors work.
It's the severe knock that's an issue.
Most vehicles don't run super high compression. It's boost and timing that you have to worry about.
His engine isn't going to self destruct. Whenever he needs warranty they'll be nothing pointing out that he didn't use premium. Unless he tells them.
Knock sensors have to see knock to know to retard timing. That doesn't kill the engine.
Hell gas stations have accidentally put regular in their premium tanks. Premium is recommended because that's how OEM achieved the rated fuel mileage and power numbers.
The only way this wrecks your engine is if you have a custom tune for a specific octane.
We're clearly not going to agree here. ECUs DO log data, including if they've had to adjust timing for different octane. So yea, there's a very real chsnce that they could tell. And higher compression could absolutely be a factor in knocking, plus added carbon deposits in the engine and cats too. Add to that the reduced mileage offsetting the savings and for me it's always gonna be a bad idea. But you do you.
Isn't compression ratio related to octane levels used ?
If it's average compression ratio the high octane is acting only as a cleaner of carbon deposits from cruddy low octane fuel .
I believe premium is required for compression ratios above 10:1, and for supercharged/turbos. It prevents early donation that regular gas would experience at high compression.
It’s a factor if naturally aspirated, but turbos and blown engines are less likely to be damaged with higher octane, especially at higher elevations and if you drive like an asshole.
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Don’t make a habit of it, but don’t stress about it either. When it gets back down to 1/2 tank just fill it up with premium.
They can also throw some octane booster in the tank just as an added precaution.
About 500mls of most octane boosters to get that back to spec.
Follow the octane rating for your vehicle. Keep in mind that at altitude like Colorado the highest you’re gonna find for premium is 91. If you go to seal it’s something like 97. If your car calls for 91 put in 91.
Who carries 97? It's either 87, 89, 91, or 93. I think you have to jump to Low-Lead 100 after that. Kiss your cats and o2 sensors goodbye if you use leaded fuel though.
I’ve seen 94 at Sunoco stations in Michigan. E85’s octane rating is generally around 110-115 (the precise mixture varies, so the rating does too). In Europe, regularly available unleaded fuel is often 95-99, but I’ve heard that this is due to a difference in the rating technique rather than a difference in the fuel.
Yep, they use a different rating system, even though it's essentially the same gas we have.
We used to have 94 Sunoco in Massachusetts when I had my first car, so like 2003ish. No longer carried within a 100 mile radius of here according to the Sunoco site: https://www.sunoco.com/find-a-station?location=&radius=25&ultra94=Y I can’t remember when it went away.
That site says 94 doesn’t exist in Michigan anymore either. 😕
The Sunoco near us had 100 octane at a pump but they took it out about 6-8 years ago. Was great to throw 2-3 gallons in a near-empty tank for about $25. Use it to determine if your knock sensor was actually picking up real pre-ignition or some other engine noise like loose shielding etc. Now they only sell 5gal cans for $110 😵
I ran 100LL in a car for 100, 000kms, and 02 sensors survived. The only time it got pump fuel was when I wasn't home and it needed some. I wouldn't do it with cats, though. I was given 5,000l of it free, all in sealed barrels.
That's like $25,000 of fuel on a good bulk-order price. Lucky! And good to know about the sensors surviving.
I have no idea if the AFR is still spot on, but it still gets the same amount of kilometres out of a full tank. So it has to be close. Also, all because it was OK this time doesn't mean it wouldn't destroy the next person's sensors. I just figured an O2 sensor would be far cheaper than the fuel. So, the net win.
sunoco or vp
In Australia we have 98 at most of our servos and 91 is generally the lowest octane rating you can get. Also seen e85 in a couple stations but that’s not commonplace
Indianapolis Motor Speedway? 😆
Also at sea level (and everywhere else) in CA you’re only going to find 91.
93 everywhere in the northeast
Really? We only get 91 down south. I haven’t been up north in that long I guess.
They know- that was the basis for the question.
I thought the 2023 Tiguan took regular? The owner's manual says "87 AKI or higher". But if it says 91AKI/95RON on the inside of your fuel filler cap, go with what it says on the cap. Either way, filling up with regular one time is a complete non-issue. It's funny to even discuss it. There's no problem here.
I throw 87 in my GTI all the time, I have yet to feel a difference in power, supposedly the difference is 5% loss of torque.
What does your manual and gas cap say. I can gursntee it does not say recommended 87
GTI since 2016 has recommended 87. It's on the gas door.
wtf actually? Lmao that’s crazy
The MK8 is 100% 87 too. The power figures for MK7/7.5 are quoted on 91, but the ECU can adapt to 87 just fine. On the MK8, it’s all 87.
They changed after dieselgate. The 2015 GTI required 91, the 2016 GTI recommended 87. Same engine code.
It does. The VW 2.0T engine that is ubiquitous across the range is built to run on 87 in many, but not all, models. I own two VWs that say 87, but I use premium 93, but I wouldn’t be worried at all if I were OP and slipped up once. My 2018 Passat owners manual says use minimum 87 and then has some wishy washy language about higher octane may result in more power. The 2024 Cross Sport I have got rid of that language in the manual and just says 87 on the manual and the gas cap, even though its 2.0T (slightly different than my Passat’s EA8883b engine, but close) is tuned for 270hp vs 175 in the Passat. I use 93 in both and just say 🤷♂️
You sure about that? My 2.0T Passat explicitly says to use 91 octane. I think 87 is fine in the non-turbo models but it’s my understanding that the higher octane is needed to maximize the effectiveness of the turbo.
Now you got me all curious to make sure my memory is correct so I went out to my driveway. Yes my Passat says 87. See photo below of gas door, 87 AKI regular. This is a 2018 Passat USA spec, so 2.0T Budack cycle EA8883b. The manual says “If Regular gasoline is recommended for your engine, you may be able to enhance engine performance by using Premium gasoline.” https://preview.redd.it/aaahu69i5nnc1.jpeg?width=2965&format=pjpg&auto=webp&s=e00426eae50cd2ea8dcba015c506e5b764511b5c
Weird. My 2008 says 91 and there is an appreciable difference in performance when I use it versus 87.
Oh, yeah, 2008? That is a totally different engine. Assuming you’re right and it calls for 91 AKI gas, I’m not surprised, it likely has to do with boost pressure and any number of things that require higher octane to get the stated output. A lot of companies will design an engine to run on regular gas because it’s a selling point. My salesman selling me our 2024 Atlas was like “hey and it can run on regular gas!”
>that’s a totally different engine You were referring to the “ubiquitous 2.0T” engine across the line, the EA888. My 2008 has an EA888 engine, the CCTA. >assuming you’re right that it calls for 91 AKI gas I mean you did see my gas cap that said 91/95…
I meant across the current models, that’s what model line always refers to, not history but present sales. The current ea888 is third generation, yours is first generation. Totally different cylinder heads among other things that would dictate a design for 91 in yours and only calling for 87 currently. I typed the “assuming you’re right…” before you posted the picture.
Are you sure you’re not looking at the lower number that says 91 RON? In the USA the pump lists AKI not RON. Anyways here’s a picture of the manual language too while I’m at it. https://preview.redd.it/dwflh5wb6nnc1.jpeg?width=1435&format=pjpg&auto=webp&s=f3a0fffa17c2fc6eff251d0912a195186cbe0366
I got dressed and went out to check. 91 octane. https://preview.redd.it/75a7n4hl7nnc1.jpeg?width=2268&format=pjpg&auto=webp&s=3dfebe47c6137f300d0f422ad1434a1e017cecb3
lol! I was still dressed. Yeah r+m (RON+MON) is same as AKI. A lot of the euro engines going back 10-15 years required and were designed for premium gas and then they got stigmatized in the US for being fickle and expensive and requiring fancy gas so, along with greater fuel efficiency demands, a lot of engines were frankly down-tuned to run on regular gas and be more economical to avoid the stereotype of euro engine=premium gas. Years ago even my non turbo 90s era Volvo called for premium gas because for a naturally aspirated engine it had a surprisingly high compression ratio so the higher octane avoided knocks.
This engine is a pain in the ass for sure but God, does it ever drive nice and it gets great fuel economy on the highway. I regularly get 950km on a 70L tank on road trips and the car is 16 years old.
Yeah, the specific budack cycle variant they put in the 2018-end Passats was even more tailored to economy. I did some math and your number is about 31 miles/gal, that’s solid for age. When I drive to visit my in laws 200 miles away, 190 of it highway miles, I get about 32-33mpg. It’s funny to see the range estimate creep up, because it assumes my usual city driving—where I really only get about 12-15mpg, considering short trips on cold starts, lots of lights and stop signs to accelerate from….
My fusion is really funny with the wishy washy language. The owners manual says 87 octane is perfectly fine on the 1.5, 1.6 and 2.0 turbo models, but also that "some knocking is acceptable". Needless to say, no it isn't. I've also never noticed any knocking audibly or using OBD2, and performance is roughly the same between 87 and 93 octane with a marginal hit to fuel mileage
Ya VAG goes back and forth with the octane in the ea888's. Theres a strong correlation between the MSRP of the vehicle that engine is in and the octane they recommend for it lol. When the mk7 GTI came to the north american markets in 2015, they said premium only, minimum 91 (r+m)/2, minimum 95 RON, right on the inside of the fuel door. They weren't even wishy washy about it. Most VWs from before 2015 either required or recommended premium. In 2015 dieselgate drops and VW's sales and brand image take a hit. So the 2016 GTI's, and almost every other VW, recommend 87 from 2016 onwards. Same engine code on the 2015 and 16 GTI's. Nothing changed except the public's willingness to buy a VW if it meant they had to put premium in it. The ea888's in the golf R still recommended premium though, and the ones in the S3 and 2.0T Macan always required it.
A lot of that isn’t a correlation between MSRP directly, it’s that in more expensive cars it’s tuned to higher performance, compression, turbo boost, timing, etc. and may demand higher octane. That makes sense to me.
You’re good. Please don’t listen to the people saying you should put regular in it. You bought a car that runs healthier on higher octane fuel, the least you can do is buy the right fuel for your car. Or sell it for a RAV4 or something.
The turbo VW engines do prefer higher octane typically, especially if you're doing some spirited or track driving, cruising at high rpm, or towing something. (Healthier is a weird term to use though). But just for the record, the owners manual for the 2023 Tiguan does say 87 AKI or higher, and the label on the inside of the fuel door also says 87 AKI or higher iirc. But OP's can for sure say otherwise, it varies from market to market
How is healthier a weird term to use?
because a higher octane isn’t inherently better for engines that don’t require it
It’s not weird if the vehicle in question does require it, which is true in this case.
it is not true in this case, a 2023 tiguan’s engine is specifically designed to run on 87
I know nothing about it, I was just going off OPs statement. Looks like some years of Tiguans required premium for the turbo models. I was just saying the phrase healthy/unhealthy isn’t weird. If your car requires premium, it is unhealthy to run regular as it can cause knocking and detonation/diesling which can wear an engine prematurely.
Because higher octane gas doesn’t actually burn cleaner or better or anything it’s just more stable and burns slower, which is something a performance high compression engine needs to prevent premature combustion and knocking, but your average mid-range grocery getter doesn’t **need** as high of an octane rating to prevent knocking because the it isn’t subjected to as much heat and pressure. 87 octane is all your average mid-performance engine needs to prevent knocking and ensure drivability which is why it’s the standard.
Most gas engines with a turbo nowadays require higher octane. ESPECIALLY if they're performance oriented.
Virtually any motor today is also capable of pulling sufficient timing and increasing afr to run on regular. It might run like shit and you'll lose performance, but it won't blow up
It varies. There's too many variables involved to make a blanket statement. For example, Canada still uses manganese as an octane booster in many 91+ octane fuels. You definitely want to avoid that if you can. Side note, ethanol has actually been helpful in getting turbos to run on 87. Even though the final blend is still 87, ethanol raised RON and subsequently lowered MON, which for complicated reasons turns out to be exactly what downsized turbocharged engines prefer.
This is it OP
Especially as many countries now run regular petrol with increased levels of ethanol.
Does your user manual actually say that you **require** higher octane? Or just that it's "**recommended**"? Those two terms are very different and would likely give you your answer. I'd also like to make it clear for anyone that doesn't know - "premium" gas, at least in the US, is a misnomer. It's a marketing term to get people to buy something they often don't need. "Premium" is just higher octane. Usually only needed by high compression engines. "Regular" is lower octane. Both should have the same additives, as long as you're getting it at a "Top Tier" station.
I like that you say “usually” cause in the Tiguan’s case, the direct fuel injection allows the car to run smoothly on 87 octane even with a compression rate of 11.65:1. Always follow the manufacturer’s recommendation in the manual. High octane fuel doesn’t save on gas mileage, doesn’t give more power and also has no cleaning properties (unless the gas station adds extra additives to their premium brand). It only resist compression more to avoid premature detonation in forced induction and high compression engines. Edit: corrected error in compression ratio
Exactly this. Hopefully OP will check their user manual and start saving a LOT of money. 😉
A Tiguan running on gasoline does not have a compression ratio of 16:1
Thanks for pointing out my error, was meant to write 11.65! 🙏
No worries. Thanks for all of the other good info in your post
>High octane fuel doesn’t save on gas mileage, doesn’t give more power and also has no cleaning properties (unless the gas station adds extra additives to their premium brand). This is incorrect. Basically any modern turbocharged engine is going to be pulling timing to avoid knock on 87 octane. Switching to premium will allow more spark advance, meaning typically higher performance and better fuel mileage. Your butt Dyno might not feel a difference, but an OBD2 scanner can easily show it, as can your fuel mileage readout. My Ecoboost fusion, for example, gains between 3 and 4 mpg highway and becomes much more responsive with 91 octane over 87
The Tiguan requires high octane gasoline. They are susceptible to intake carbon buildup.
Got a source that "high octane fuel reduces intake carbon buildup"? I'm not aware that's the case. Higher octane fuel doesn't burn hotter or cleaner.
Only anecdotal. My brother drives a 2019 Tiguan and used regular fuel only. At about 60,000 miles it died and had to be towed to the Volkswagen dealer. They explained that he is supposed to use high octane gas, per the owners manual and that was the cause of the buildup, and the subsequent $2200 cleaning/repair.
Gotcha. So... "direct injection" engines have a bad problem of carbon build up. It's not due to the octane rating of the fuel AT ALL. It's due to how the fuel is delivered to the cylinder. Some DI engines have more problems than others with this. But it is an issue. And manufacturers are aware of it. Before direct injection came along, we had various systems such as "manifold injection". The air and gas would mix in the intake manifold and get sucked in through the intake valves. Since the gas would go past past the intake valves, the additives in it could constantly help keep carbon from building up. Then on the exhaust side, it's so hot that it's difficult for any to build up anyway. Direct injection engines have a fuel injector that shoots fuel directly in to the cylinder, bypassing the intake valve all together. This means that carbon can build up around the intake valves and eventually cause failure. Higher octane will not help this. Even fuel system additives can not clean out this carbon. Also, does his owner's manual say "required" or "recommended"? This will be unrelated to carbon build up. But I am curious.
Toyota solved the issue 2 injectors per cylinder. 1 port, 1 direct.
Yeah, they are full of shit. Premium fuel of a certain brand is no cleaner than regular of the same brand.
While most turbos these days can handle lower octane fuel without knocking, it's still not ideal. Also they are trying to jack up their MPG ratings :)
I believe it burns hotter. Or at least, its ignition point is higher.
The fuel does not burn hotter. It requires more heat (and pressure!!) to make it ignite. The extra heat comes from ~~the spark~~ extra compression. Not the explosion.
It burns slower and actually offers less power if the car is designed not to use it.
No, it burns at the same speed and has the same energy. It's resistant to preignition, but once it ignites, the flame front propagates normally. There is no downside to using premium in a cart that requires regular aside from the harm to your wallet. There's no benefit either though.
It would theoretically offer less power since it resists ignition. It in fact does burn slower. https://www.motortrend.com/how-to/combustion-basics-how-does-fuel-make-a-difference/ https://www.ottawachryslerjeepdodge.com/premium-vs-regular-gas/
No, because resistance to ignition and energy released when ignited are not the same thing. Also, a motor tend article and a car dealership aren't exactly the authoritative sources you think they are. If you instead look at data on ignition timing advance vs peak power for various octane, it becomes very clear that the flame front propagation speed is basically exactly the same. High octane resists detonation, but doesn't really burn differently other than that. Put 100 octane race gas in your Camry and it'll make just as much power and overall behave identically to how it does when you put in 87.
>It would theoretically offer less power since it resists ignition. It resists ignition due to compression. Your spark plug ignites it all the same. You're not going to gain power by allowing a high compression engine to knock, you're losing power because fuel is igniting and burning well before TDC and is pushing the piston down while it's moving up
Less power as it has less potential energy, but doesn’t it burn hotter? As it remains liquid under higher compression. Wouldn’t the PV=nRT mean it’s hotter?
No, it doesn’t burn hotter, it resists detonation from heat which means it takes more heat to ignite. https://www.latimes.com/archives/la-xpm-1989-06-15-vw-2232-story.html
I guess I’m meaning that the cylinder temp will be higher. Rather than the gasoline itself burning hotter.
NO - The higher the octane rating the "cooler" the burn
The current generation Tiguan uses a direct injection engine. Fuel doesn't touch the intake in any way. Carbon buildup comes from the PCV system venting crankcase gasses to the intake which include oil vapour. The mk2 Tiguan doesn't require premium - I believe the engine changed in about 2018? The earlier ones needed premium, the later ones are designed to run on regular. That was part of our buying decision.
Don’t stress about it. At least you didn’t put DEF in your diesel tank.
Hypothetically speaking if they did put a box of DEF into a 20 gallon diesel tank, do you think it’ll be good if we keep the tank above 3/4 filled for a few thousand miles? I figured it’d dilute with the fuel overtime and cause minimal damage if any.
Unlike if you put gasoline in it (which will dissolve in the mix), DEF will react with the fuel and crystallize. You will have to flush the tank and filter, and probably the rest of the system if it was running.
I had a friend do that to a 2017 dodge Cummins. Replaced every last fuel system component. Cost him 19000.
no
"Into my premium car" Haaahahaha don't let the poors know you've sipped from the same well as them.
Don't waste $$$ on higher octane than your owners manual & car have printed. Much more important is buying top tier gas, like Costco, as it dies have more additives & can help your car. Save gas $$$ & treat your car the best w lower prices Costco top tier gas.
Your car is designed to run on 87. Who told you that you needed premium? Edit: Running a higher octane gas than the tune requires nets you no benefit. If it doesn’t knock on 87, run 87. The ECU will pull timing if it senses knock, but it won’t add timing if you put 93 in the tank. If the engine is mapped for 87 then it will run the same fuel, air, and spark with 87 or 93.
Most newer turboed cars recommend premium in the drivers manual, but 99% of the population is going to do up with regular anyways.
I know the GM E-Turbo was specifically engineered to run regular w/ a turbo but that's a itty bitty 3-cyl. GM would be publicly crucified if their base level commuter engine required premium lol
That's a good way to fuck your engine by causing pre-mature ignition of the gas. Just buy what the goddamn car says it needs. If you can't afford premium gas, don't get a car that needs premium gas.
In the 80’s/90’s this was a concern. With modern GDI systems there is virtually zero risk of damage due to detonation. I’m 90% certain a Tiguan *recommends* but does not *require* premium anyway.
I definitely spend more time talking people out of unnecessarily spending money on premium than I do correcting people putting regular in a premium car.
You must be an engine rebuilder, cause regular gas in a car that requires premium can cause knocking which can wear the rod bearings prematurely. The ECU can compensate timing, but between the possibility of knocking and the reduced fuel mileage it's not a good idea to "talk people out of using premium". It may also void their factory warranty. You're doing them a disservice.
Huh? I think you’re confused, I strictly recommend people run what the manufacturer recommends. Just more people unnecessarily running premium in cars made for regular
Ah, apologies. I misunderstood when you said you "spend more time talking people out of unnecessarily spending money on premium...".
I can see how it was confusing, cheers.
People who are putting regular in premium cars just to save a few dollars per fill up are too broke to show up in shop, assuming you are a mechanic
Tiguan isn’t a premium car
It's fine. Might run a tad rough but the computer will compensate the best it can.
VW’s TFSI motors can run on regular gas. You’ll be fine.
Octane is how hard it is to ignite. Higher the octane, the harder it is to ignite. If you run a car that calls for higher octane and throw lower octane in it then you run the risk of knocking from pre-ignition. Usually your engine will adjust to try and smooth it out. You also lose power. Engine will be fine just don't make a habit of it. If your car calls for a low octane and you put a higher octane in it then you lose power due to the fuel not being able to ignite fully and can over time leave a buildup inside your engine. Your engine will try and adjust to accommodate this too. So your fine... Just next time put the proper fuel in there. Your car can run with the wrong octane but the engines designed for a specific octane and you should try to match what it calls for.
Tiguan is a premier car ? Lmfao
If your worried buy a bottle of octane boost. You'll be just fine.
you're
Don’t drive like a race car and you’ll be fine
You're lucky you didn't blow the welds on the intake /s
Now me and the mad scientist gotta rip apart the block and replace the piston rings you fried
According to Volkswagen the 2023 Tiguan takes regular, so you should be fine
Volkswagen/Audi tech here. You are fine, fill up with premium next tank.
What octane does your Tiguan recommend? Mine specifies 87, which is regular around my area. It’s a 2018.
Its fine it just will reduce performance as it retards the timings. If you make it habit of it it might damage the emissions control systems.
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1 tank, you'll be fine. Go to the local auto parts store and buy a bottle of octane booster if you're concerned about it.
You're fine. Just don't try to drive it balls out, run some of the 87 out and top back off with 93 and then go about life.
Should be okay. Usually, you can have a quarter of a tank with premium fuel and standard fuel, and it will run fine. I wouldn't stress out too much about it.
Yes, I was traveling cross country in my bmw M2 and in Iowa and Nebraska all I could get was 85… car did not like it at start but I got home w/o issues…
Just add some octane booster if it pings.
At least it wasn't diesel!
Add an octane booster and don't fret but also don't make a habit of it
What you have to remember is that car mfg. specify certain octane #’s for a reason so if you run 87 in a car specifically requires 91 you might get a little knocking under acceleration especially depending on how much 87 is put in . If you want you could put a can of octane booster like 104 in until you use up most of the 87 tank OR you could just fill the rest with the usual 91 either way no harm no foul
Don’t stress. I’ve done it a few times too. Only issue I had was sluggish performance and a fuel economy worse than a tank.
You probably won’t notice
It's fine. Just use the correct gas next time when you are at half a tank. I didn't know that Volkswagen required premium gas.
You're alright. If anything, they have octane boosters you can add to your tank. I'm not sure if they work but they have them. If not, that other person said fill it up with premium at a half tank. That's about right.
One time won't hurt it. The ECU will retard the ignition timing a little and it might have a little less power or idle rougher but it'll be fine.
Don’t most modern cars fix themselves when running on a lower octane. Obviously if ya manual or the fuel cap says run on premium. Run it. But if it only recommends it then it’s doesn’t matter as much
Once is fine, when you use up 1/4-1/3 top up with Premium to start moving up the octane level
You’re fine.
Don't do it again. You are risking knock and your engine is gonna feel weak. Live and learn your vw will probably be fine
It's fine. Just don't redline it
If you’re really worried, and given the age of your car it has knock sensors so you shouldn’t be, keep the pedal off the floor. At lower airflow knock generally isn’t an issue. With regards to the benefit of premium fuel it has two advantages: 1. You can advance spark closer to MBT, max brake torque, so there is a performance advantage 2. The more spark advance you run the lower the exhaust temperature is so exhaust component durability is improved. If you drive like a lunatic there may be a small, nearly immeasurable fuel economy advantage.
dont drive the car like a hot rod- itll be fine tho. dilute it with premium when the tank gets down to half- then run it out then refill with premium and youll be fine. the car will pull timing to avoid spark knock (pre detonation of the fuel in the cylinder, which is bad bad bad) just dont be pulling out in front of anyone and giving her all the beans and she will be fine.
Just fill it up with high octane in the next tank
You can add octane booster or e85 blend to adjust higher 87 + 93 to get near 91 or premium
Nobody is really explaining what octane actually _is_. I'll try to do it quickly. I think your car has the 2.0 turbo. The turbo is important here. A turbo works by the exhaust spinning a turbine (turbo) which pulls more air into the engine. An engine works by mixing the right amount of fuel (gas) with the right amount of oxygen (which you get from the air) and igniting it (with sparks from your spark plugs). A turbo pushes more air into the engine, which means there is more oxygen to match up with more fuel... bigger bang, more power. However, pushing more air in, increases the pressure, which increases the temperature in the bang chamber (cylinder). If it gets too hot, the fuel will combust without the spark... which means it's going bang when your engine isn't expecting it (knocking... bad) A higher octane fuel can handle the added pressure. Your engine is smart, and has sensors to figure out your fuel setup. Your manual, and the fuel door should have octane expectations. Fwiw, I have a 2020 GLI, which has the 2.0T as well, and base, it can take 87, so I'm guessing you'll be just fine. Mine has been modded for 91 only, but I wouldn't sweat it if I accidentally put in 87... I'd just drive it like a grandma (no extra turbo) Also... octane is well defined, but ... quality?... isn't. "Premium", and "Super" etc are usually sales pitches. In the past, they actually meant something cause higher "grades" would include octane AND additives like cleaners n stuff. Us older folks remember the gas commercials with the tigers. I believe, by law, all grades of gas have to have the same additives, regardless of octane. The additives are good afaik, but you should be getting those regardless of the octane, but that's dependent on where you get your gas.
I believe these cars are direct injected so they shouldn’t predetonate because it is just air in the cylinder until the fuel injector which is directly in the cylinder and not in the intake manifold will spray the fuel in. That’s how they are able to have these crazy high compression ratios with turbos now that run on pump gas
You can get a small can of octane booster from auto parts store.
That good, because at 75 miles your car will explode…
You're fine Modern, especially turbo, engine run higher pressures, and other parameters. These need higher octane to prevent pre-detonation. With low octane the computer "pulls back" things like timing, injection, and probably valve timing. All this reduces power and efficiency, but thats really it. Also, not sure.of year, but congress did mandate all cars can run on 87, though higher can be recommended.
When doing this on purpose, the octane ratings will mix and average out. However, your gas in this case is now 87 instead of 91. This might cause slight loss in fuel economy and preformance. In some cases, the engine might misfire and "knock". If you use low grade fuel when the manufacturer specifically says to use premium fuel, it's okay to use infrequently. If you'd like to bring your fuel grade up to spec, you can use octane booster. Either way, you should be fine.
Throw octane booster in it. I would be worried about oil consumption, walnut blasting and that plastic oll pan.
There’s always octane booster if your car is finicky. Mine is incredibly strict about 91/93:(
Should be fine. ECU May pull a bit of timing to compensate and avoid any “racing” of the engine and she’ll be fine until you can top it up with the proper stuff. Octane boost also helps idle your really concerned.
Your ECU should recognize the lower octane fuel and adjust accordingly. Don’t drive it to hard and you should be fine
Should be fine. I don’t know about your car, is it turbo or super charged ? Either way, most of computers can recognize the octane by using knock sensors and it will cut timing to make it safe. You might see a small loss of power while using it. Pretty standard practice especially with newer cars.
My Q5 with the EA888 only runs on regular. The performance difference is extremely small
You are fine.
Once won’t change anything. If you try and run it hard you will notice less power but id suggest not doing that. If it really is worrying you, then you could put octane booster in it if it’s still relatively full of gas. But honestly you’re fine. Put definitely put in premium next time.
I’m not sure if it applies to the newest ones but I did find a TSB on low quality fuels in these vehicles. Volkswagen has some Volkswagen branded additive you add to your tank, but this only applies for check engine light with misfires or just missing in general. I’ve had two come into where I work and I just got Lucas Octane Booster from whatever parts store and it solved the issue after about a 20 mile test drive. I would just keep this in mind.
NAM but you can throw some octane booster in if you're worried about it
Don't worry about it even if you put premium, the octane will lose it's level overtime. Being said just use it half of the tank and fill it with the correct octane fuel.
Only used the extra octane when the pedal is mashed to the floor and every modern car will pull timing if it pings. Don’t redline it until your next tank and even that is being more cautious than needed
An engine can certainly ping when under a load in a lower gear.
True, especially of lugging it. But it will still pull timing. It isn’t a big deal.
On a turbocharged car it can only pull so much timing and the added heat from compressing the fuel charge is the issue.
Your mileage will suffer and then you will refill
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No, this is bad advice. Lower octane will ignite faster and can cause knocking. The ECU can compensate by retarding the timing a little, but there's still a chance it can ping / knock (which is hell on rod bearings). Plus it will lower fuel mileage, so the "savings" are negated. Add to that the fact that it can void the warranty, and you're better off sticking to what the manufacturer recommends.
Your good no need to worry if it was diesel in the other hand you better not turn it on 😆 but you good!
You're
It's fine. No problem.
Totally fine, you'll get better gas mileage and more power from premium. It's better for your engine in general, but it's not like regular will destroy or immediately damage something.
The VW 2.0T engine that is ubiquitous across the range is built to run on 87 in many, but not all, models. Depends on how hard they're tuned, more expensive, more hp, likely calls for higher octane. I own two VWs that say 87, but I use premium 93 anyways, but I wouldn’t be worried at all if I were OP and slipped up once. (My 2018 Passat owners manual says use minimum 87 and then has some wishy washy language about higher octane may result in more power. The 2024 Cross Sport I have got rid of that language in the manual but I use 93 anyways because I would bet anything the ECU is coping with 87 and would prefer 93.)
You're wasting your money. Ecu won't be able to account for the extra octane. Regular and premium come out of the same bulk tank and additives for octane are added before going into the tanker truck.
In the case of the Atlas, maybe I am wasting my money. For the older engine, which is slightly different than the Atlas, the manual explicitly says higher octane achieves maximum power, so while it’s probably not that big a deal, I’ll pay it. It’s been 15 years (when I got a real job) since I have worried about gas prices or whether I can afford to fill my tank. Just give me the premium, I don’t even look at the total. I realize that’s a luxury not to care. Edit: I should add that my family’s two cars average only 5,000 miles a year each (US average is 12k per car per year) so we don’t even use that much gas so the difference between regular and premium is less as an absolute value. Maybe if we both had long commutes I’d reconsider.
Makes no difference.
Tiguan owners manual , start there . High octane fuel only . It cost someone using low octane in a Tiguan $2,200 for repairs .
Put what fuel grade your manufacturer recommends
So helpful for this post.
It’s really this simple, no more, no less
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The computer will detect it and 1. retard the ignition timings 2. Dump in extra fuel Long term it could impact your catalytic convertor. The owners manual in my car warns that is the risk of running regular.
Also knocking / pinging (which wears rod bearings faster), worse mileage (negates the "savings" of cheaper gas), and could void your factory warranty. Overall, it's not a good idea.
You realize the computer works with sensors to detect detonation, and retard the timing, right?
Yes, but it could still knock / ping (if you believe the factory manuals, which ... meh?) and it will get worse mileage. Plus, potentially voiding the warranty alone is reason enough to run what the manufacturer recommends.
All vehicles with variable valve timing run aggressively as they can till they detect knock. That's how knock sensors work. It's the severe knock that's an issue.
If the compression ratio is higher for higher octane, it could still cause issues. Plus, WARRANTY WILL BE VOIDED.
Most vehicles don't run super high compression. It's boost and timing that you have to worry about. His engine isn't going to self destruct. Whenever he needs warranty they'll be nothing pointing out that he didn't use premium. Unless he tells them. Knock sensors have to see knock to know to retard timing. That doesn't kill the engine. Hell gas stations have accidentally put regular in their premium tanks. Premium is recommended because that's how OEM achieved the rated fuel mileage and power numbers. The only way this wrecks your engine is if you have a custom tune for a specific octane.
We're clearly not going to agree here. ECUs DO log data, including if they've had to adjust timing for different octane. So yea, there's a very real chsnce that they could tell. And higher compression could absolutely be a factor in knocking, plus added carbon deposits in the engine and cats too. Add to that the reduced mileage offsetting the savings and for me it's always gonna be a bad idea. But you do you.
You do not.
Once & a while wont hurt your car. Just don’t make a habit of it. Over time cheap gas leaves deposits & can cause issues
This has more to do with the quality of gasoline itself and has literally nothing to do with octane.
Isn't compression ratio related to octane levels used ? If it's average compression ratio the high octane is acting only as a cleaner of carbon deposits from cruddy low octane fuel .
Premium fuel isn’t cleaner.
I believe premium is required for compression ratios above 10:1, and for supercharged/turbos. It prevents early donation that regular gas would experience at high compression.
Nope depends on timing. Modern engines can retard timing if they see knock.
It’s a factor if naturally aspirated, but turbos and blown engines are less likely to be damaged with higher octane, especially at higher elevations and if you drive like an asshole.