The cheap walmart cans vent and will evaporate your gas. I've gone to nato type cans. But you can use liquid gasket on the cheap cans
Huh. I've had 6 of these in a 10x10 shed for over a year and never noticed one hint of gas fumes. Haven't had any problems with the gas itself either. Maybe it's because I almost never gets over 85 degrees up here? Maybe if they get hot they vent?