Break-free CLP will remove rust if left long enough, motor oil will just prevent it. I had a pistol with some surface rust that I sprayed with break free and put in a ziplock bag until I could get it refinished, tucked it away and forgot about it. When I remebered it, the rust was gone. I do the same. Not just motor oil, but transmission fluid, gear oil, lucas, etc. All goes in the same jug. Work and home used to be a 100 mile round trip, I managed to collect almost a gallon. Since i would never end up using it all on guns, I put some of it in the engine of my beater truck when its running low... The lady wears contacts, the empty jugs for her contact solution work well. Pain to get the lid off though.