use a pencil eraser to remove any rust spots and lead it with the lead, then oil it good and it should stop rusting....unless you're in water environment.
At the auto parts stores they used to sell Slick 1 in a red big spray can with a black top. It has Slick 50 in it and you can douse a gun & wipe it out in rain forever and it just doesn't rust! I've tried Breakfree, Eezox, RemOil, 3in1 Oil, military stuff, etc. Nothing I have found keeps it from rusting longer than this stuff. Can of it lasts forever & I clean all my knives/guns with it. The paste wax idea mentioned above is a good idea as well. Works wonders on .45 mags to keep them rust free and they are "fast" on the reload. If you use the pencil eraser (smoky mtn knife works actually sells a rust remover eraser for knives) and lead the thing...if you have a touch up blue pen it goes right over the lead and blends perfect on firearms or dark knives. Most AL knife handles are painted black and it wears off after a while leaving silver...A sharpie works to cover the nicks to Surefire lights as well on the finish & blends perfectly. I tend to only carry dark colored knives as shiny things are just one more thing for the bad guy to shoot at.