Chris thats right,in the article they diluted with water,would like to know the degree,50 to 1, 25 to 1 etc. Have done the rear of black beauty with 4000 wet and dry and then system one,came up mirror but that was with a prepsol cleaner.Would like to do the front with 4000 again but not with prepsol but I/alchohol as the cleaning agent. I think prepsol is great but very aggresive, maybe I/alchohol would be just as good.I'm just anal I guess ;);););)