Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

Mostly, I use Coleman Camp Fuel (White Gas) with a 20:1 - 40:1 mix with Marvel Mystery Oil!

Obviously, I don't feel that the mix ratio is super critical, but the engine will tell you if it is or isn't getting enough. I like to see just a bit of oil in the exhaust, not a whole messy lot of it. Different engines do seem to prefer different ratios, at least in my experience!