The owner's manual for my "new" 1995 Audi 90 Quattro V-6 states that premium fuel is recommended but the label on the gas cap door says the minimum is 87 octane (which is regular). What should I use and what do others use? It there really any noticeable improvement in performance or engine life from [more expensive] higher octane?

Thanks.

 

I use 93octane primium all the time, winter will switch to 89 octane for better performence at cold maybe.

 

The Audi motor comes with high compression and a knock sensor. You should be able to use 87 octane without any problems but for maximum performance you want to use 93 octane. It also depends on your driving style. If you live at the red line then you will get a few more ponies. I use high octane in my 91 100Q year round. With my own observation I get about 26MPG on the highway when using 93 and I get about 22MPG with the medium grade. In the winter the mileage will be less due to cold weather and denser air.

 

I have just made the switch from 93 octane to 87 octane. As a direct result of rising gas prices. I have used 93 exculsively since I have owned the vehicle (3 yrs.). i have been using 87 for about two months now. I drive about 70 % highway and 30 % backroads.

I have noticed a very very slight performance decrease, as well as a lot more knock under load. Otherwise it runs just fine. I don't feel that the increased knock is anything to worry about.

 

Knock is VERY sirious, Knock destroyes rings and fries cylinders.