Is 89 octane bad for my car? Not your normal ? [Archive] - Forum


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02-01-2008, 07:12 PM
Here's the deal, I can cross the state line and get 89 octane w/10% ethanol for about $0.20-$0.30 cheaper than 87 octane. I've been doing this ever since I bought the car. Will running 89 octane hurt the engine in the long run seeing as how my car is meant to run 87? The reason I'm asking is that I've read that since 89 burns slower, it'll leave more deposits in the engine.

Mike Jung
02-01-2008, 07:37 PM
Don't worry about it ;)

You are doing everything ok.
I to would also only use the 89-octane that is blended with up to 10% ethanol.
(& not the 87-octane that is blended with up to 10% ethanol.)

Ethanol alcohol is a natural octane booster.
89-octane ethanol blended gasoline is really like 87-octane gasoline with up to 10% ethanol added to be a final product of 89-octane.

Recall awhile ago: About 87 vs. 89 Octane Gasoline (

PS: The Ethanol also helps keep your engine cleaner :D

Mike Jung
02-01-2008, 07:43 PM
Here is another old post by me...
So with the US this summer changing their gasoline formulation to ethanol blends.
To stop using MTBE (methyl tertiary butyl ether).

...The ethanol in E-10 Unleaded adds two to three points of octane to gasoline...

After having a read of this thread: About 87 vs. 89 Octane Gasoline ? (

Will you still use 87-octane gasoline (after they blend it with 85-octane gasoline & ethanol to make it 87-octane) ?

When I fill my Mom's Sunfire GT with Sunono ethanol (up to 10%) blended gasoline; I always reach for the 89-octane (which is 87-octane gasoline blended with ethanol to make 89).

02-01-2008, 10:06 PM
Thanks Mike.