Bob Johns

I live in Denver. I told the dealer I was experiencing some fairly significant turbo lag with my new s4. He told me that at high altitude, I would get better performance with 85 octane gas than I would with the 91 octane I had been using. This seems counter-intuitive. Can this be right?

Crapple0

if the dealer really told you this, get it in writing, with a guarantee that they will cover any associated repair costs. only THEN use the low octane.

Nick Gustas

What altitude are you at? I've noticed a significant difference in lag between 5k and 10k feet.

S4@last!::Now B7 RS4

I am in colorado too, I have run 91, 94, and 100 octane in my car and notice a difference with higher octane. I woud not recommned 85 octane in these cars. If you are noticing significant turbo lag, there is definately something wrong. Either there is a leak in the pluming, or a failed turbo. Have they checked all the hoses? Notice any other symptoms besides the turbo lag?

ppith

You're kidding right?! See my post on 101 octane in a stock S4!!!

Jeff Vader - boscoj

I have heard this too with rotary Mazda's, the 91 goes off too quick, you get a bigger later bang