Quote:
Originally Posted by Texas Coyote
The manual says that 87 octane is the lowest that can be used in the Fit.... The ECU will retard the timing to not have the engine ping with lower octane fuel and allow more advance with premium and improve your gas mileage and performance as well as contributing to less carbon deposites in the combustion chamber..... The 2007 model has a 10.4 to 1 compression ratio which would have called for leaded premium (ETHYL) gasoline back before unleaded fuel and ECUs.... The premium fuel used in other parts of the world is rated as high as 97 octane and Fit owners that use it in their cars continue to do so because it makes them faster and again get much better fuel mileage they claim justifies the price.
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Take it from this old refinery engineer: there isn't enough difference in the energy content of premium vs regular to pay for a 5% difference in price. And the difference in additives isn't that much either. And the difference in octane ratings now vs way back when is simply because carburators simply weren't precise enough to meter gasoline at the precision that prevents to pre-ignition.
You can run premium gasoline but unless you're on track at speed its a waste or unless you climb steep hills. Otherwise there won't be a preignition problem and no retardation will happen.