Octane question
Thread Starter
AudiWorld Member
Joined: Feb 2010
Posts: 56
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From: Newport, NC
Octane question
will be picking up my new s4 in early may and i have a question on gas. What is the lowest octane everyone is running with.Reason i ask is that i was riding with a friend who has a 335xi and he pumps 87 for around town and 91 or 93 when he is roadtripping. Any thoughts? Can 87 cause damage to your engine? thanks
AudiWorld Member
Joined: Feb 2010
Posts: 382
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From: Greenville, WI
Any high-performance engine benefits greatly from higher octane content fuel. Not only will the engine make more power, but it will also run cooler in the process. Almost all VAG engineered power plants are high-compression, especially those which are forced-induction (turbocharged and supercharged). The most efficient combustion is produced using higher octane molecule content fuels, but be aware not to run too much octane. Too much octane can also damage an engine if it's not designed to run it.
I've always run the highest octane pump gas I can readily find (usually 92-93 R+M/2 here in the Midwest). However, always follow the recommendations from Audi as listed in your owner's manual. IIRC, they recommend premium octane content for almost all their engines. Stay away from 87 octane with that engine, especially when stopping/starting often (i.e. city driving), accelerating hard, driving in high ambient temps, etc. These conditions, when coupled with lower octane fuel, can lead to pre-detonation and misfires. If you want that engine to run properly, run premium. If you can't get the min octane level you need in your area, consider an octane additive as a last resort. Just be sure you know how to mix it properly.
I've always run the highest octane pump gas I can readily find (usually 92-93 R+M/2 here in the Midwest). However, always follow the recommendations from Audi as listed in your owner's manual. IIRC, they recommend premium octane content for almost all their engines. Stay away from 87 octane with that engine, especially when stopping/starting often (i.e. city driving), accelerating hard, driving in high ambient temps, etc. These conditions, when coupled with lower octane fuel, can lead to pre-detonation and misfires. If you want that engine to run properly, run premium. If you can't get the min octane level you need in your area, consider an octane additive as a last resort. Just be sure you know how to mix it properly.
AudiWorld Senior Member
Joined: Sep 2003
Posts: 783
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From: Seattle, WA
Read this article someone copy pasted in the A4 forum in regards to Octane.
https://www.audiworld.com/forums/sho....php?t=2777936
https://www.audiworld.com/forums/sho....php?t=2777936
AudiWorld Member
Joined: Feb 2010
Posts: 382
Likes: 0
From: Greenville, WI
Don't be misled by the opening statements in that article. Read on, and you'll find out why it's so critical to run higher octane fuel in the 2.0T and V6T engines in the A4/S4. It's no joke, and can make all the difference in the world in high-compression engines.
AudiWorld Senior Member
Joined: Sep 2003
Posts: 783
Likes: 0
From: Seattle, WA
The ultimate conclusion of that article should be...
"However, more aggressive engine management schemes, especially those found in turbocharged or supercharged vehicles, can turn up the compression to a high level, requiring much higher octane gasoline to avoid knock."
"However, more aggressive engine management schemes, especially those found in turbocharged or supercharged vehicles, can turn up the compression to a high level, requiring much higher octane gasoline to avoid knock."
Last edited by ShadowJet; Mar 14, 2010 at 01:45 PM.
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