Dawn Ultra or Borax to clean epdm roof?

My trailer is not in covered storage and exposed to the elements all year. I used the Protect-all cleaner and then the protectant on my roof about twice a year. Looked great after doing. It did nothing to protect or extend the life of the roof. After 8 years the black was starting to show through. Now I coat it every two years with Hengs rubber roof coating. I for future trailers I think I will refrain from doing the cleaning and protecting thing.