I can agree with a few of the people on here who used motor oil. I was at the lake last summer, when a rainstorm hit, not knowing my tent leaked since it was new, I stupidly left my gun under my sleeping bag while we were getting hammered with rain. After the rain stoped I picked my 9mm out of the puddle of water in my tent, and said "&@#$@#@#.!!!!!!" I had no gun oil of course, so I took oil off the dipstick of my truck a few times, and lubed it up. No rust.