Scrub them with an all purpose cleaner. Then dress them with something like autofinesse revive as a non permanent fix, or wipe down with panel wipe as well then dress with GTechniq C4 for a more permanent fix
Whilst I agree with the chipping comments, and I'd not usually paint anything on a car unless its a last resort, the front grills on 172/182s goes blue instead of the usual faded black. All you do with any form of restorer is make it shiny blue instead of mat blue. IME.
To be fair, aren't these about £35 from the Stealers? I'd buy a new one if you're that bothered. Then protect it. But not always cost effective or viable in NZ!
Whilst I agree with the chipping comments, and I'd not usually paint anything on a car unless its a last resort, the front grills on 172/182s goes blue instead of the usual faded black. All you do with any form of restorer is make it shiny blue instead of mat blue. IME.