update: I'm finding I hydro2 about every 5-6 weeks, but it's a base car that does not dust, and I'm in Florida good weather...z51's may need it more. I really notice that the nooks and crannies of the caliper don't hold dirt like they used to, that's worth it right there...also, I'm doing 4-5 spritzes per wheel with a special one shot spritz on the caliper...
after you dilute it (mandatory) , the bottle will last about 6-8 months at this pace.....