Koolponycar

I just read in the paper where about 7 states are going to go ahead with winter fuels etc., Tennessee being one of them. the colonial pipe line down temporary. So are we going to get some gas that might not be up to par so to speak. I have a 93 performance tune running great, should I go back to stock after this tank of shell and wait until things are back to normal? How are you all affected, I know its bad in Texas as this effects everyone and I really feel for the people in Texas. We all should help by at least giving to help them, at least that's what I am going to do.

engineermike

Winter fuel has a higher vapor pressure to help with cold starting. It more readily vaporizes, but the BTU content is lower. Basically, it won't hurt anything but fuel economy and the effect is something like 2%.

Koolponycar

So that explains the gas mileage, thanks! My new tires being more aggressive and heavier don't help either, lol!

JCH841

Yes, octane (anti-knock) the same, just burn a little more to make the same power.