[QUOTE=Lazarus;31499]This is one of the things I don't understand. Why does it work sometimes and not others. Why does it do 1 mpg gain and a 3 mpg gain other times. QUOTE]
All I know is at one station near me, if I dope up the tank I can make gains, whereas, if I dope up at another station nearby, I never gain a mile. I think it has something to do with the quality processing of the fuel they put in the tanks and which refinery it comes from.