there is an additive that flat *** works. I used to carry a can of it in the trunk, and would add it at each fill up. it worked on a 600 horse 406 sbc. called MACH 1--qt to 16 gal. if I remember it right, use to be fairly cheap, but now is as hi as race gas. like I said, it use to work darn good,but I haven`t used it in yrs. something else that will work, b 12 chemtool , carry a can w/ you for every fill up. $2.99 a can at atwoods, used it after the mach 1 went up -----bob