New England weather can get nasty, so having a generator and some gas is almost a necessity.
I bought several 6 gal cans a few years ago, and one of the plastic caps split, and would not seal.
I went on a quest to buy a replacement cap, but as was my experience in the past, they seem to keep changing the threads and size, and none of the replacements would work.
I bought a new gas can last time, but hate to trash a perfectly good gas can for lack of a working cover.
I washed the broken gas cap in alcohol to get any residue off. Then cut some small strips of my favorite aluminum tape, and carefully taped the cracked cover back in the correct shape.
The type of plastic they use does not glue well, and there is a lot of stress on the cap when tight, so I got out my trusty epoxy putty, and mixed up enough to totally cover the cap.
I rough sanded the plastic cap, and made some light saw cuts to give the epoxy something to attach to,
and I made sure to get some under the bottom lip of the cap, so the broken cap was totally encased in the putty. The epoxy cured overnight, and the cap now works just like new, and I expect that this cap may last longer than the virgin ones.