I dont use any protection on any of my blades but I protect some of my tools that see more of the FL humidity and spray from the Gulf.
I found out that the WD40 Specialist line, particularly the Gel Lube and the Penetrant sprays are staying longer when applied to clean metal than any other protectant.
Years ago it was a sort of standardized test done by a Glock forum member, and those two came up on the top of most tested lubricants. If i have to ship a blade l usually use light coat of Remoil, in fact most of the gun related products wil work just fine.
For aluminum l use Mil-Com TW 25B, it was recommended to me by Sig when i got my 226 aluminum frame. I cant say if it bonds with the oxidation differently, generally l use very little lubricants on my guns or knives.
I used to treat new guns with Miltec dry bonding lubricant, read somewhere that with the time it would absorb moisture but l didn't observe anything like this, every gun that i properly treated with it doesn't have trace of rust or spots. I did try it on few fixed blades that I'm using constantly but l clean those on regular bases so l cant really say if its working as intended or not.
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Edit: I found the test that I've seen in Glock forum, the link points to different site, hope it's not a problem to post it:
It's a fairly long read but IMO very helpful if one is looking for specific gun or just metal lubricant/protection product.
COMPREHENSIVE CORROSION TEST: 46 PRODUCTS COMPARED
image courtesy of the author of the article - DIY_guy