I had no idea WD40 was such a good rust preventer. Remember a "test" from a few years back where one half of a nail was dipped in Break Free and left outside for a year. The undipped half was rusted away severely while the half dipped in Break Free looked almost new. Same sort of quasi-scientific study.

One thing about WD40, though. It is not good stuff to put in complicated mechanisms like locks and firearm trigger/stirker assemblies. Tends to turn into a gummy substance over time.