Thread: 87 vs 91 octane for better mpg?
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Old 01-22-2008, 10:23 AM
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bwilson4web bwilson4web is offline
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Real Name: Bob
Location: Huntsville, AL
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Default Re: 87 vs 91 octane for better mpg?
Quote:
Originally Posted by oscars2212 View Post
ok I searched a little bit for an answer to my question, but didn't really find anything. A simple question:

will my car (a FEH, so it does not "require" premium gas), get better gas mileage using premium gas (91+ octane) instead of regular gas (87 octane)?

I'm not asking about engine performance in terms of power. I know some cars require premium gas to get peak HP. I'm asking strictly about effect on mpg.
My testing in Huntsville AL revealed 87 octane, Shell, Exxon and Chevron had the highest energy content per gram. All other brands and octanes had about 11% less energy than these. I did see some evidence that at nearly maximum ICE power, the 93 octanes were less bad but not as much energy as the 87 octane Shell, Exxon and Chevron.

Bob Wilson

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