Originally Posted by THE TECH
I was thinking about finding out of we can just get the o-ring that's on the cap and maybe double them up for a better seal.
do not double up the o-ring. it will really leak then. you can easily remove the o-ring, measure it, and then buy one that is thicker. that can be tricky though as what i think you want is more depth while maintaining ID and OD to fit. whatever you buy, make sure it is of the right material and durometer to withstand the duty. sounds like you want a custom fit gasket which any o-ring and gasket shop can make. just give them the dimensions and material specs.