the simplest way to think of parkerizing is to treat it like cast iron. Just don't ever de-grease it with strong solvents etc. Always keep wiping something oily on it. It really doesn't matter what. I sure as heck would not go buy grease just for this. It's very easy to over think this too.... it's not a critical issue. I've used kroil, PB blaster, 3 in 1 oil, fluid film, various CLP products, synthetic gun oil, paste wax, etc etc... heck Vaseline would work fine. Just don't use KY and you should be A-OK