Which fuel for 4.0

[brabenec]

Hello guys,
here is the thing. I live in Europe and we have either 95 RON or 100 RON equivalent to 91 and 93 in the USA.
The label in fuel tank states minimum 95/91 on my 2018 S6 Prestige.
However every Audi mechanic says use premium fuel 100 RON which is obviously better for this kind engine. (more power, less carbon, ...)
Ok, I can buy premium fuel but I do have a free fuel card from work but that only work on normal 95/91.
I am thinking if I should be spending money on premium or keep filling with normal but buy fuel additives like BG 208, SC2 etc. which will clearly saves me lot of money but should improve normal fuel to premium level?

Thank you for advise.

[pantsoftime]

95 should work fine without additives. A lot of states in the US don't even have 93 (100) and it's not an issue for the 4.0.

[VinnysS4]

Its 91 here in the states. 92 for non ethanol. My car runs fine on 91 octane. 2015 s6 4.0

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[Alabama]

here is the thing. I live in Europe and we have either 95 RON or 100 RON equivalent to 91 and 93 in the USA.
The label in fuel tank states minimum 95/91 on my 2018 S6 Prestige.

The general advice in other AZ threads is that for a car with an OEM tune, 95 RON is sufficient and using 100 RON just wastes money. If you get an aftermarket Stage 1 tune, you would probably need 100 RON and be able to take advantage of the higher octane. Another factor is the quality of the detergent additives in the specific brand of fuel independent of octane level. In the US, gasoline that meets high standards for this kind of quality use the term "Top Tier". I don't know if there is an equivalent testing organization in Europe.

[brabenec]

The general advice in other AZ threads is that for a car with an OEM tune, 95 RON is sufficient and using 100 RON just wastes money. If you get an aftermarket Stage 1 tune, you would probably need 100 RON and be able to take advantage of the higher octane. Another factor is the quality of the detergent additives in the specific brand of fuel independent of octane level. In the US, gasoline that meets high standards for this kind of quality use the term "Top Tier". I don't know if there is an equivalent testing organization in Europe.

Thanks, well we also have lab tests in Europe and if you do not meet strict specifications the seller will get fined quite a lot.
I am running Stage 2 + downpipes btw.

[Optimus247]

Hmmm ... stage 2 + down pipes ... Use the higher octane ....

Should have stated that in your original question ... Lower octane will get you by (the computer will turn back timing to prevent pre ignition) till you can find the better fuel

[Valpo A7]

For the OP, Audi RECOMMENDS (not REQUIRES) the use of 91 octane (95 RON) in the owners manual and in the next sentence they state that 87 octane (91 RON) can be used. The downside to using the lower octane rating is slightly reduced engine performance. On 91 octane the engine should produce 450 HP, on 87 octane the engine might produce 440-445 HP.


For my A7 I have been running 89 octane now for the last 87,000 miles, not sure what the original owner used before me. My car is now at 229,000 miles

[AudiInMyA7]

I use 93 but thats cuz i flashed a tstage 1 tune on it for 93, so thats what ive been doing. I also have only used 93 in the time ive owned it (just under 2 years, 20k miles)


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