Quote:
Originally Posted by BavarianFanatic
I don't bother wasting money on premium fuel. It runs just fine with 7 Eleven 87 octane.
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I "think" I read somewhere that ANY car sold in the U.S. MUST, by law, be able to run on 87 octane fuel.
Me, I'll continue to use premium unless it's an emergency out in the boondocks where the gas station ran out of premium.
Just an FYI from:
http://www.economist.com/blogs/babba...octane-ratings
I know most of you guys already know this but for those that don't....
Quote:
On the face of it, then, a motorist would seem ill-advised to use regular petrol in a car with a high-compression engine. That was certainly the case in the past. But cars today have sensors that listen carefully for the knocking sound, and instantly retard the ignition system when they detect that detonation is about to happen.
The delay in delivering the retarded spark allows the piston to start moving downward on its expansion stroke before the ignition actually occurs. That provides additional room in the cylinder head for the gases to expand and thereby reduce their damaging peak pressure—and so burn in a more controlled manner.
To sum up, if the car’s handbook says that premium petrol is “recommended” (rather than insisting it is “required”), then the engine will automatically adjust itself to run smoothly on a lower octane fuel. Because of the retarded ignition, the engine will, of course, produce less power, and have slightly higher fuel consumption. But the poorer fuel economy is likely to be outweighed by the savings at the pump.
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