I prefer to use soap and water but nowadays due to water restrictions or park rules that isn't always possible. I use the was/wax waterless cleaner and it does a great job even on the roof. It just takes more of it and more rags to wipe it and the dirt off. It seems to leave a nice finsh and removes a good deal of the oxidation. It's an expensive option with all the accessories but I'm pretty happy with the final results.
