Back in the day I used to help clean up cars for the auction. First thing I was told, soap first, not water, we usually used white wall cleaner for things under the hood, do not let it dry, wipe with a brush then water off the area. Tires, wheels, calipers are done the same way, I carry that over to everything I wash, even my hands. Don't know why but it works, again if you wet it first it won't come clean. Doing that way I have no problem using the regular spray cleaners. If it doesn't come clean the first time, let dry completely then apply again.