Outside of my new barrel for my 870 has a bit of rust. Doesn't look like it's gone through the bluing. I know to lightly use 0000 steel wool with oil, my question is, what kind of oil do I use. Every damn bit of instructions I read only says to use "oil", but fails to mention what kind of oil. I have ten different kinds of olive oil in my pantry, will that work? I don't know because it doesn't say anywhere!!!! Rant over, please help.