all

With regard to PS21, I've been using it on my Fikse's on the Vette for four years now and it's absolutely tops. I started using it on my past MB wheels in the early 90's and it's the best IMHO. The first time I had to clean the nine spoke's on the beast the PS21 continued to be my choice and does an excellent job. I've tried some of the stuff available at the local auto stores, but none of those chemicals can touch the cleaning and gentleness of the 21. I don't like how much it costs (I buy the gallon refill size from autopia and it's like $58.00!) but my experience with the other chemicals is sub par at best. Pretty sure Porsche, MB and BMW all recommend it for their clear coated and painted wheels.
My personal take and have no affiliation or benefit from the manufacturer.
FEVR