A friend sent me this info. Add toluene to the gas... http://www.elektro.com/~audi/audi/toluene.html Has anyone seen, evaluated or actually tried this? Back in the 1970's we would habitually add 4 to 5 gallons of high octane to 16-20 gallons of cheap gas all at the same. As I recalled this was suggested by the "Shell answer Man". I thought it worked for me... I regularly did this for my big Ford (460) van used pulling a fairly heavy travel trailer through the moountains. I also had dual fuel propane setup which pretty much eliminated any carbon buildup which also helps prevent pre-ignition knock so I don't know which was the most help for me... I did drive primarily on propane. Any input from anyone? _____________________________________________________________________ Ralph Ausmann - Hillsboro, OR - > http://mysite.verizon.net/res79g4m/ Classic AMX Club of Portland - http://clubs.hemmings.com/classicamx