The idea is to coat it with the soap, let it set, and then power wash it off. Lather, rinse, repeat as needed.
I use "Krud Kutter" as a degreaser and like it better than most. Simple Green is a good general purpose, but not as good on grease. Some stuff just isn't going to get clean that way, and some stuff a power washer just doesn't work well on period. I'm all ears on something better.
