Quote:
Originally Posted by david in germany
You should do a bit of research on it. Higher octane does not equal more power. Higher octane does allow for more aggressive timing in the engine. The lower octane is less stable than higher octane. you should run the lowest octane your vehicle can take for the most power and efficiency.
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This isn't entirely true. There exist vehicles where "premium fuel is recommended for maximum performance". I owned a 1993 Nissan Maxima SE that fell into this category. There are modern Toyota's and Cadillac's (just two examples) the fall into this category as well. Their ECU's are set, specifically, to run the lowest and highest octane gasoline and
will adjust to perform better (i.e. produce more, verifiable HP) if higher octane fuel is used. This is not to be confused with, say, the clause in your BMW owner's manual that says basically "you can use 87 octane if you
absolutely have to, but fill it up with premium as soon as you possibly can". This statement in the owners manual is always in cars that are designated "Premium Unleaded Fuel Only" (I have seen it in every manual from Mercedes, Audi, and BMW that I've owned from model years 1995-2016). If you have no such statement regarding premium fuel, then you are indeed pissing away money putting in more expensive gas as the ECU will not adjust parameters to give you better performance. Then, of course, there's those of us with tuned engines where you
really should use fuel with the octane rating required by the tune that's flashed.