This may be of interest to some. I just spoke with Dave G. at Red Line. He said Red Line intentionally formulates their oils not to clean that well as they don't want to disrupt deposits that can come lose and cause more problems within the engine. I asked him if he thought the esters in Red Line contribute to a cleaning effect and he said no, they are not aggressive.
So for all these years it has been assumed Red Line is cleaning when in fact it is not. Remember there are many different types of esters. I believe HPL chose theirs based on having high solvency.
Food for thought....
I will agree with what Dave G has said, to a certain extent since I have talked with him on the phone awhile back.