Any suggestions would be appreciated from you guys. We recently started using Meg's wheel brightener at our shop ; it doesn't work very well at all , unless the wheels are fairly clean already. Mixed it 4:1 as per the directions,not nearly strong enough. We clean alot of dealer and wholesale cars here,so most wheels are pretty nasty, and vary from plastic wheelcovers, to painted factory wheels, etc. We also use a pressure washer if needed to blast the junk off. Any tips,tricks? or should we go back to our old product (non-Meg's) ?