You can try Penetrol for making them look good again. Wipe two or three coats on about 24 hrs. between coats. It will eventually start to flake off after about a year then just pressure spray and re coat.

A guy here has a 89 H-18 and he wipes all of the metal down with it. Looking at it you'd think metal was all new.

You can find it in the paint dept at Home Depot.