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Re: fuel octane - what is your opinion? Open to all... (more) Posted by Ari [Email] (#2847) [Profile/Gallery] (more from Ari) on Thu, 26 Apr 2001 10:27:48 In Reply to: fuel octane - what is your opinion? Open to all... (more), Shahn, Thu, 26 Apr 2001 03:41:12 Members do not see ads below this line. - Help Keep This Site Online - Signup |
Octane is a rating of how resistant a fuel is to knock - higher octane fuel contains no more power than lower octane fuels.
Basically, run the lowest octane fuel that keeps your engine from knocking under full load. Any higher octane fuel is a waste of money. It does your engine absolutely no good. Now, the Saab APC is pretty clever - if it senses knock, it will reduce boost. So at some point, if you drop the octane rating of the fuel low enough, you'll notice a cutback of boost under high load conditions - like accelerating up a hill on a warm day. Even then, the engine management system is protecting the engine.
If you want to save money, you can use low octane fuel in a Saab turbo engine and take the performance hit. But the manual is only a guide that covers 99% of the engines out there - you only own the one in your car. And each engine is different. I have had 3 2.0L turbo engines. The engine in my '86 900T needed 91 octane to get full boost. At 89 or 87, the boost would drop off under hard acceleration.
My two '88 9000T's, which have exactly the same engine type, run quite happily on 87 octane. I can get full boost under all load conditions with 87. So I have no reason to spend the extra $$ for any higher octane.
So if you run a few tankfulls of lower octane fuel in your car, and you still get the performance you want, then by all means, use the lower octane fuel. Gasoline companies put $$$ into advertising, giving you the idea that higher octane fuel will make your car perform better. Not exactly true. You need a certain octane to achieve the full performance your car is capabile of. Any more is a waste of money. And that octane varies from car to car.
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