Re: Fuel Grade
Ed T,
You give up too easily.
For starters going from 87 to 89 octane is a really small jump.
So even if there was some advantage, it would be small.
I used 93 octane, and saw a 1.6 mile per gallon gain, but a majority of my driving is around town, where the advantage of a higher octane would make the most difference.
Because around town your engine is under moderate load most of the time trying to get you back up to speed after stopping, the low to mid RPM torque, and horsepower are increased due to the more advanced spark timing.
This translates into spending less time in lower gears.
The reason the octane would not make much difference out on the big road is because the engine is not under the heavy load it normally sees around town.
So the computer can run the spark timing at a less aggressive advance to match the lower octane, and the decreased loading on the engine which causes spark knock.
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