im replacing my roof mounted ariel but the original whole is to small fort the thread of my new ariel. Im fine with drilling the whole but i.ve noticed there's some bare metal where its been fitted previously. Even though the rubber base should keep water out once fitted what can i do to give it extra protection? Some sort of primer or base coat, were only talking tiny little bits not a full on respray. The quality of finish doesnt mater as it will be hidden but dont want bare metal if i can help it. Many thanks luke