So my dad has been an auto-tech for most of his life. He recently started working for a friend of his who is not only a gear-head like my father, but also a gun-nut, like me. My dad knows that I do heavy-duty gun cleaning jobs on the side, so he recently gave me a can of Zep Super Penetrant spray. His boss gave it to him to give to me, saying that's all he ever uses to clean his firearms. Swears by the stuff. This is automotive cleaner of some kind, and I've never heard of anyone using it on guns. Has anyone here ever actually tried it? Seems to me like it might be good on rusty screws/locked up parts on older and/or severely neglected weapons, but I'm still wary about using it until I know more. I've always been a big CLP man myself, using very fine steel wool on the tough stuff when necessary.