Quote:
Originally Posted by ptjones
Minimum octane for CMAX is 87, max ethanol % is 15 and regular in NM is 86 octane  , I use Premium 93-91 octane.
Paul |
That's done because lower air density means 86 at altitude is equivalent to 87 at sea level. It's a non-issue.
Quote:
Originally Posted by ptjones
Premium is worth 1-2 mpg for me, not quite worth the extra cost, but I like the extra range  I also have 2016 F150XLT SC 4x4 2.7L EB with 23.3 mpg mostly HWY 15k mi., with 36gal tank, I use regular.
Paul |
Unless you derived that difference scientifically, it's likely all in your head. The anti-knock agents in higher octane fuels contain less energy, i.e., Premium gas has less energy per gallon than 87. It's not a big difference, but it's there.
You're basically claiming that by burning a more expensive fuel with less energy content, you are getting better gas mileage. Unless your vehicles are adapting their compression ratio to take advantage of the higher octane fuel, which is generally not possible unless they're somehow changing stroke, bore or valve lift/duration to compensate.