I use Zanio products also, I think they are the best. I use the clay bar when I apply new Zanio polish works great. Just make sure you keep it lubed as you use it, and follow the instructions. I also use it on my windows, but I use a seperate clay bar from the one I use on my paint. I use window cleaner as a lube when I use it on my windows. It has removed water spots from my windows. The windshield may be too pitted or scratched to come clean. http://www.zainostore.com/mm5/merchant.mvc