carmudgeons.com - Question for Michelin Pilot Sport A/S 3+ users

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Quote:

Originally Posted by Josh (PA) (Post 541313)

do they change from summer to winter gas formulas down your way? Might just be coincidental timing.
The difference between summer- and winter-blend gasoline involves the Reid Vapor Pressure (RVP) of the fuel. ... The US Environmental Protection Agency (EPA) says conventional summer-blend gasoline contains 1.7 percent more energy than winter-blend gas, which is one reason why gas mileage is slightly better in the summer.

Excellent observation. I didn't even think of that.

Yes, we usually change to a winter blend here and performance does exactly what you have written.

Quote:

Originally Posted by rumatt (Post 541316)

That's what I was wondering too

Yeah, can't believe I missed that. I'm usually pretty good at pointing that out to others, LOL.

Quote:

Originally Posted by clyde (Post 541322)

I'd trust hand done math before an OBC reading. Those things aren't exactly consistently consistent.

I didn't realize that OBC readings aren't very consistent. I've been logging my mpg stats since August 2002.

I should do the hand math and see how far off those OBC readings are....