Like the others have stated. Your fine just burn the entire tank and restrain yourself from really getting on the engine. It'll be fine.

LOL!

Exactly. Octane rating is merely the ratio of octane to heptane in gasoline. Given the volume of the Z's tank, and assuming you filled up, prolly puts you right around 91-92.

Duh, 2 gallons mixed with the rest 93 octane is probably like=92 octane...dont worry be happy.

I thought that gas with AKI 87 or RON 95 is possible with VQ37. :shakes head:

RON 95 = (approximately) AKI 91

Yes, you are right. Just finded, that AKI in USA is different to other ones used in different countries. AKI used in USA is 4-5 points lower. In other countries using AKI it is between 8 to 10.

Based by twice read this article Octane rating - Wikipedia, the free encyclopedia

Strange, that is recommended RON 98 in Europe - see no difference to 95.

98 RON is roughtly 94 AKI.

You can get a pretty accurate estimte by taking the RON value and multiplying it by .95 to get the approximate corresponding AKI (i.e., 98*.95 = 93.1; 98 RON = ~93AKI).

Most ECU's have an ignition map that starts higher (for example, after a reset) than you see over the course of driving and pulls timing based on knock detector activity and also transient conditions like air, water, and oil temps. It will add timing back in as conditions change, of course.

So, threotrically, higher is better, at least to a point. You would probably see diminishing returns past 95 AKI /100 RON without a re-tune.

Also as you start creeping into higher and high octanes (well over 100), it gets harder to ignite (especially when cold) meaning potentially fouled plugs, higher emissions, etc. but no more power without a re-tune of the spark maps (unless it was under so much load and such harsh ambient coniditions that it was seeing some knock, of course...)

So basically anything betwen 91 AKI (95 RON) and 95 AKI (100 RON) is good, with 93 or 94 AKI probably being about optimal on the factory tune in normal, but spirited, driving condtions.

If you were never going to put much load on the engine (i.e., drive slow, wihout any sudden acceleration or high speeds), a lower octane would work in a pinch to keep from getting stranded or something, but it's far from ideal or recommended.

The manual states you can use a lesser grade gas if needed.

^^^ Right -- to avoid being stranded. But beating on the car with < 91 AKI fuel is ill advised.

The manual also says to not do more than half a tank, and to refill with the proper octane ASAP, if memory serves...

Really useful info Jordo!

My TT TFSI 2.0 (new model) done 80000 kms without any issues on RON 95. That engine is RON98 only (in BWA version). But actually I didn't see any difference in long term use. Maybe it is caused, that gas stations are selling RON 95 as RON 98 (I could be wrong, but in Czech is different Shell V-Powe Racing than in Germany, which is our neighbor).

By long term I mean around few thousand kms and really spirited driving sometimes - 240 km/h for one hour on autobahn.

What is really strange to me, is fact if is recommended AKI 91 in US, why is only RON 98 in Europe? Maybe I'm wrong because search function doesn't work to me for now.

In the US, due to ultra strict emissions laws in California, pretty much all vehicles sold in the US that require high octane fuels are tuned to operate normally with 91 AKI.

That said, many gas stations in the rest of the US don't carry 91, but have 92, 93, and even 94 AKI.

You can even get 100 AKI at the pump in some Sunoco stations -- although it costs nearly twice as much as 93 AKI, and isn't particularly useful unless the spark map has been tuned for it... or maybe if you wanted to be extra cautious running laps at the track on a hot day in the summer.

Don't know if you are getting 95 or 98 RON or whether the label is accurate -- there's also MON, which is slightly different... so maybe 95 RON = 98 MON? Not as sure on that one...

Anyway, either 95 or 98 RON is fine, and neither should result in much (if any) of a significant difference in performance unless you are pushing it really hard in harsh conditions, in which case the higher of the two would be preferred but probably not essential.

I thought ethanol boosts octane, so you get less knock not more.

I think the reason he refers to it as crap isn't due to the octane rating. All things the same E85 will run leaner than regular gas. I saw a video where they were talking about the differences and the E85 needed roughly 30% more fuel to be happy.

I think E85 has a totally different stoichometry than gasoline (needing more fuel per lb of air would support that assumption) and also requires alcohol safe components to avoid corrosion.

Basiclaly, you can't run E85 in a vehicle that isn't tuned/designed for it.

Good, cuz I thought you were crazy for saying that lol.