it is coated with rubber, I suggest coating it with a low enginetemp paint, like no more than 500 degree paint, only to keep it from fading really.
Sand the rubber coating on it down with some 400 grit or higher sand paper, just to score it. rinse it off, and you don't need to prime it anywhere unless you have a spot where you can see the metal under the rubber. From eitehr sanding too far down, or a scratch/chip. =)