You can also consider adding two-stroke oil. It is DESIGNED to be burned without leaving ash and fouling, and is STUFFED with lubricity additives. I use TC-W3 oil at a rate of about 1 part per thousand, or 2 ounces per 16 gallons of fuel.

Gee, I guess that is also one ounce per 8 gallons of fuel, for those who can't do mental math without a calculator.