Originally Posted by Lucas McCain
It primary purpose is to displace water and prevent corrosion. Although it,s composition is proprietary,and we don't know its composition, it does serve as a light lubricant, very similar to 3 in 1 oil
WD-40 is not a lubricant, and it is not at all similar to 3-In-1 oil. WD-40 is basically kerosene, with a bit of paraffin mixed in.
Want proof? Many years ago I had a new car rustproofed. The applicator gave me a tiny bottle of solvent to clean up when it dripped out of the door vent holes onto the rocker panels. I asked him what to use if that little bottle wasn't enough. He said, "Oh, bug and tar remover will work, but WD-40 is better. Takes it right off."
3-In1 oil is oil, not mineral spirits.