You can use auto care products at twice the price if you want. I always look for a less expensive way to do the same thing. Goes back to my childhood. My parents were savers and not spenders(depression kids).
Personally I like Joy. Does not seem to be as hard on paint as Dawn. All depends on what you are getting off. The Reliable we sell will clean the real bad stuff off with ease and not hurt your paint.
Ken's comment about "Reliable" is valid. I have been using it to do the difficult cleaning jobs since he talked me into trying it and I agree that it is the best I have found.
What I was thinking of with the comment about using auto paint care products was in terms of one of the wash/wax products or the wax products. I don't have full body paint on the motorhome, but if I ever buy another new one it will have.