i am certainly NOT going to beat you up for using engine oil on your firearms. many of us do, including myself. firearms are not exactly stressful applications, not even ar-15's. if you think about the huge load placed on a high-performance auto engine (not your everyday run of the mill 4 cylinder chevy), the heat generated, the huge torque loads, the thrust put upon cylinder walls and pistons, that is stressful. and for many, many years, conventional motor oil was all there was. then came racing oil, which is regular oil, with an additive package. then, mobil decided to do us all a huge favor, and decided to sell to the general public synthetic oil that was specificly engineered for HARD, HARD use. i have tried both castrol gtx 5w30, and mobil 1 on my guns. either seems to do the trick for me. i have decided on mobil 1 0w40 for my guns, and that is what i am going to stick with at least until this bottle is gone. which will probably be long after i am dead. in any case, the reason i opted for 0w oil is i do hunt, and sometimes it get really cold and nasty. i do not want the firing pin to be sludged up by oil that is to thick when that buck of a lifetime comes up out of that swamp. the reason i went with 0w40, is i also shoot my pistols when it is over 90 outside, and when you shoot semi autos faily quickly in hi temperatures, i want the film of oil to be stable, and not fly off. pick whatever you feel is best. just give proper consideration to temps and type of firearm, and the stress put on those parts. as for storage, for long term storage, i personally subscribe to straight STP. i stored my fathers browning for 20 years after he died with it. it took a while to get all of it off and out of all the nooks and crannies, but there was absoloutly not one spec of rust on this gun, not one. the only thing i ever did to it through all of those years was to look at it once every few years, and make sure it was doing fine. it is hard to beat that kind of sucsess.
