My cam cover and intake to a lesser extent are dull and oxidized. They did have the yellow coating but that was removed when parts were cleaned by a machine shop during a rebuild in summer of 2000. What is the best and easiest way to polish these? Would some kind of aluminum polish and a cloth buffing wheel work? I would like to do this with parts on the engine because I can't do without the car at present. To kept it shinny, is there some product like a spray on lacquer that would be good to use?