Gentlemen, I wouldn't be too quick to apply Mobil 1 or any other synthetic motor oil to your firearms. Use Oils designed for this purpose, i.e. Rem Oil, Hoppes, even 3 in one oil or WD40. Motor oil is strictly a lubricant and does not have additives which inhibit rust. Some motor oils actually attract and hold moisture.
Just be careful what you put on your firearms.