If air didn't get into the can it would implode. The best defense you have is to use good oil that has the stabilizer in it plus keep the can sealed and in an area w/ low temp variations. Marine Stabil, Startron, CRC etc will also help combat the issues related to alcohol in the fuel.

Any can is going to expand/contract with temperature.
IF it doesn't vent, the sides will crumple in when cooling.
The problem is with the moisture in the air.
Each "cycle", a bit more moisture is drawn in with the air exchange and the alcohol in the gasoline just loves to absorb it.

I try to store my containers of fuel (including the tanks on the equipment) either next to the brim to cut down the dead air space (thus less air exchange each cycle) or empty so not to have the alcohol to absorb moisture.

Hmmm: Guess i was just lucky! I took out the gas can (plastic/red) that sat all winter in a tin cabinet, outside, poured it into my lawn machine, and it started and ran! I installed a battery in my Craftsman lawn tractor, that has sat outside all winter, covered up with a leaky tarp, and ran it for an hour for yard work. No additives. HMMM. Could it be Ceasaar Chaves gasoline?
I use it all the time, and never have problems, nor do i add anything to it.??

Thank you all very much. That was very helpful information. May I also ask: How does Marine Sta-Bil and Startron combat the alcohol in 10 percent ethanol gasoline? Does Startron and Marine Sta-Bil actually decrease the amount of ethanol in the gas, or might some other process be at work?