I touched up the door window frame on my Scamp
(Hehr) with black satin. When I took it to the glass shop for new glass, they thought the frame was brand new. Little did they know it came off a 25 year old trailer. I used Rustoleum brand, spray can
On edit: I should have mentioned I put the frame in the bathtub and used a scrub brush and Tide laundry detergent to degrease it and get it sparkling clean... first.