WD 40 is a great short term lubricant for things like rusty bolts on equipment, also a decent solvent. As a sort of expirament after reading about the thousands or permutations of various oils I decided to make my own. Some left over Castrol Syntec oil, looked a little thick and was thinking about it lack of cleaning assistance properties so I thinned it a little with Sea Foam. Tried it on a couple of things, so far it is awesome for smootheness. Don't know if I will keep using it not. Honestly I think the best rule on firearm is to use some, if it is halfway decent and you pay just a little attention to it, you should be fine for 90% of needs.