I think many of the posters in this topic are confused. Gas can vents were to be opened while filling or draining the can to allow the air to escape or enter as needed. The vent was supposed to be sealed tightly during storage and non-use. The vents were never there to prevent flexing of the can during temperature changes. If you did leave the vent open during rising temperatures, the vapors in the gas would escape, making the gas less explosive. Then in cooler temperatures, it would suck outside air and moisture into the can, contaminating the gas. To keep gas fresh and contamination free, you need a tightly sealing gas can. The whole environmental benefit of not releasing vapors into the air is just a positive side effect.
With that being said, My no spill cans are over a year old now and they have been flexing all along just like yours. I keep them in a low ceiling shed with no shade nearby. The cans have no stress fading, much less stress cracks or anything concerning going on with the plastic. Between my own use as well as helping family members and friends, I have tried all of the commonly available gas cans out there. No-Spill are still the best fuel cans I have ever used. Blitz cans are the worst I have tried. Metal fuel cans are expensive, plus they dent, scratch and rust easily; over rated IMO.
With that being said, My no spill cans are over a year old now and they have been flexing all along just like yours. I keep them in a low ceiling shed with no shade nearby. The cans have no stress fading, much less stress cracks or anything concerning going on with the plastic. Between my own use as well as helping family members and friends, I have tried all of the commonly available gas cans out there. No-Spill are still the best fuel cans I have ever used. Blitz cans are the worst I have tried. Metal fuel cans are expensive, plus they dent, scratch and rust easily; over rated IMO.
