[Buddy Harrison]

While I have not tried this method myself, a number of posters to this forum have stated that they clean the area to be preserved to remove oil and fingerprints and then apply a thin coat of Tru-Oil to the case colored metal surface. They indicate that they periodically, depending on the amount of use the gun gets, reapply a thin coat. This seems to be one of the most often touted ways to accomplish your goal. Good luck.