Thanks for the replies and discussion, folks! I also came to the realization that it's oxidation that needs to be prevented. Just to experiment, I took a couple of pet cocks that I had polished to a nice lustre and applied "Mother's Original Carnauba Cleaner Wax". I left it overnight in the shop and cleaned the haze off the next morning. WOW! That brass went from "nice!" to "Wow! I can see my reflection!!" I can feel the difference with a towel too. The unwaxed brass grabs the rag, and the waxed is slippery, so the wax did "take". I was also surprised how dark the applicator got from the wax application, seeing as I had cleaned them as much as possible. I think it's worth a shot! My untreated oilers faired well out in the elements last year from July until late October, so an anti-oxidant on them should be even better.