who knows what is really in there. the only thing for sure is that there is NOT gum in coleman fuel. but as to btu/lb or octane ratings, anyone's guess.

if you smell it, there is a leak. Is this typical of model tanks? I don't have actual models with gas, but I am working on it. I will make my own tanks if they leak. If it is the exhaust, it should smell like the oil used.

I would say Race gas from the specialty petroleum store, LL100 from the airport, or super unleaded from the "pump," in order of preference. the order completely reverses when considered in order of reality (the race gas is probably $5 per gallon).