Believe that's where the name "Castrol" comes from. Also used as a (racing) 2-stroke oil, but it is pretty cokey.
On a gun, very long term, I'd think there might be a risk of it gumming up the action.
I have used various veg oils as chain lubricants, either alone or mixed with motor oil. Seem nice lubricants but they do get a bit gummy (very if they are allowed to stand for a long while).
Cannola seems best. Castor oil is too expensive so I havn't tried it.
Also anti-rust treatment, and tyre treatment, but I stopped the last since I thought there might be dangerous softening of the rubber.