dridua

A couple of questions about my recently purchased '06 2.0 l. First, I know that the fuel recommendation is a minimum of 91 AKI. What might the consequences be of using 89, if any? (I haven't actually tried this octane rating...just wondering if there would be any significant issues or repercussions.) Second, I've read and heard about letting the engine idle before shutting it down (turbo), and have come to realize that there are a number of schools of thought regarding the recommended length of time to let it idle. I'm curious to hear what the forum members here think about this. And is it even necessary in the first place? Thanks.

irenesbob

I am no expert, but I had an '06 and now hve an '08 B7 A4 2.0QT. Anyway - I beLieve that 91 octane is recommended not required. Going to 89 octane may reduce performance and fuel economy slightly, but likely only to be noticed when putting a laod on the car (uphill or when hauling beefy Aunt Margaret). In any event, the car's electronics sense the knocking in like nano seconds and retard the spark so there is no engine damage or cheap sounding pinging.
Also, I think just making sure that you don't turn the car off while the it is still cooling down from a road race at the redline is the issue. I find that usually (epecially at home) the process of slowing down and makeing turns, etc. to get where I am parking gives the engine and turbo components time to cool down so I just count to 5 at idle then hit "kill".

CARlectra

In German / The Netherlands and most countries of Europe we haven't got octane 89. We have 98 en 91 en recommended is 98 and possible is 91! So be smart go for 91! And our price for 1 liter is € 1,35 google for the Dollar price!!!!!

Bob58

The EU (and most other parts of the world) measures octane rating on the RON scale.

North America uses the AKI scale.

The RON scale, generally, runs about 4-5 points higher than the AKI scale for the exact same fuel.

http://en.wikipedia.org/wiki/Octane_...en_RON_and_AKI