How often do you change your oil? all oil change is 10k-15k miles with synthetic = 1 a year? I'll stick with my original plastic cap- The designed it for a reason, I don't think it was a cost cutting measure to put a plastic cap instead of metal, the same as the links on the manifold - when the plastic links broke, something is wrong or stuck, why would you want to put a metal piece to fight the stuck device, will it ruin the engine???
PS: if I can't get my oil filter cap out, I don't change the filter. It won't kill the engine (proven with many cars) with old oil filter or old oil - running engine with lack of oil - will kill the engine which I check regularly.