I've had some bed liner on the undersides of my fenders for over 3 years - looks as good as the day I slopped it on. I believe that it was Dupli-Color, but spray can stuff, 2-3 coats worth. One caution - overspray does NOT come off like undercoating with a light solvent. You wait a few days to dry, then pick it off one speckle at a time (you really don't need to hear why I know that)