And as a general statement, the oils that always seem to test the best for rust protection, in several independant tests, are the thinner lubes. Thick lubes tend to stay on the surface, and can actually trap moisture, and produce rust faster. I found that to be a fact long ago.
The thin oils have a better ability to penetrate the surface pores in the metal and finish, and that's why they're used most often, and successfully.
That's not to say that all thin lubes are created equal. Rem-oil, G-96 Spray, Beeman MP5/B.C. Sheath and a few others always seem to end up at the top of the list in those tests. They don't always finish in the exact same order, but they usually come out fairly-close to the top.
WD40 is very good for lots of uses, including surface rust removal on guns. But it never comes out too well as a rust protectant, in spite of its thin consistancy.
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