What Octane?

[VX KAT]

I was curious about this so I actually experimented with regular vs. premium. I ran spreadsheets (I know, pretty geeky) to calculate my gas mileage based on what octane I was using and where I was buying it, in case that had an impact. Based on almost two years of testing, I'm getting 2-3 MPG higher when I use the 87 octane fuel as opposed to the 91 (or 93 in a couple of cases). I don't notice any appreciable difference in the sound of the engine or the amount of power I'm receiving, but since that's all subjective and the only thing I am actually measuring with any sort of rigour is mileage, I can't say for certain.

I do know that I am running a completely stock engine.

Great data! Any winter blend vs. summer blend data or impressions, or did you do just an overall annual average? Probably hard to determine exactly when the blend changes anyway (although seems like I've seen stickers on the pump when it's the winter mix??)

[circmand]

Great data! Any winter blend vs. summer blend data or impressions, or did you do just an overall annual average? Probably hard to determine exactly when the blend changes anyway (although seems like I've seen stickers on the pump when it's the winter mix??)

Its not like the stations use different tanks or change over at the same time. Basically the refineries change over thn the tankers pick up the new fuel and just fill up the tanks with the old fuel and it mixes