Hello, what have u guys used to help protect traditional color case hardened receivers?

I was thinking of using a poly type car wax (not a cleaner wax or abrasive wax, just a poly coating like meguiers next wax 2.0), rennasaince wax, or eezox (a clp that is good for protecting bluing resists acid fingerprints and is excellent in preventing rust). I read somewhere that carnuba wax should not be used but have no idea if that is accurate or not.

Any ideas?

I have a couple guns I'm interested in protecting one is a 1913 gun which has traditional case hardening and the other a 1970s gun which I assume is a chemical type of case hardening plus varnish but I don't really know on that one.

Thanks!