For the guy using the used engine oil that has the additive.. used engine oil is considered a carcinogen.
If you use frog lube, you are supposed to heat the metal first, or you get a gooey minty mess.
I lube real sparingly, and wipe off the excess, usually just a drop of gun oil.
Folders aren't my first choice for food prep, I think bacteria in hard to reach places is a bigger risk than consuming miniscule amounts of oil.
Looks like food grade mineral oil is the way to go, I need to treat my cutting boards too. Sounds like it is good for the wood knife scales too.
Thanks for starting this thread, and making me rethink my ways. Gonna pick up some mineral oil tomorrow.