MG42pillbox - I done a lot of experimenting over the years with my gas mileage, I get the best fuel mileage using 1oz acetone per 5 gallons of E85. A can of acetone lasts forever, and I'm saving around $1.00 per gallon on my fuel and the horsepower is amazing. You can even tell by the sound of my exhaust as I'm driving down the road. And it doesn't downshift going up hills like it used to for power, still going 55 miles an hour at the top of a hill using cruise control. Duane