With the vent caps on, they sometimes plump up like a ball-park frank over a campfire because of expansion from warm air in the enclosed space. Should I go ahead and vent 'em---knowing that at some point I'll likely have no gas in the can from evaporation? Or, leave 'em closed?
If I do open the vent, do I in fact lose gas, over a period of time? With the vents open, I don't smell gas, so don't know exactly what's going on. Maybe there is no problem with leaving the vent caps open.