[PeteH]

I would try a spray detailer to clean. If it is discolored from exhaust carbon, I use enamel reducer, then follow with spray detailer. This comes for 20 yrs of exhaust discoloration on a Big Healey rear bumper. One of the guys in our club wore thru the chrome down to the nickel repeatedly using abrasive chrome cleaners, so I stay away from anything that has abrasives in it.