On parts with cosmoline I clean the part, shoot it with Eastwood Spay Gray and then I use the Eastwood Anti Rust Inhibitor or everybody else calls it cosmoline. After letting it dry for FOUR DAYS (I'm not kidding) It is still tacky to the touch so I shoot it with Krylon Satin Clear. This makes it so you can touch the parts and wipe it clean if it gets dirty but don't rub it to hard because it will come off. I'm still trying to come up with something that will harden 100% but till then this will do.

Hope this helps.