dish soap can be used, and like the above states: it's very harsh. the problem that many detailers are split when it comes to dish soap is although it strips off wax easily, it might not be good for plastic trim, or rubber (like weather stripping) because it is a harsher cleaner.
While you can strip the wax off first, you don't have to. the thing is, prior to claying, you'll need the car to be clean (so the clay picks up actual contamination, not dirt and grime that'd come off anyways), so u might as well wash with dish soap, clay, rinse back down, then use a wax/sealant.
use plenty of lubrication, and the clay can be used on all exterior surfaces if used correctly (lubrication, surface isn't hot, little to no pressure).
oh, and don't forget to post up pic's for everyone to enjoy once your done making your baby smooootth
Linear Mode
