I have tried to remove what seems to be RainX from the windshield with the RainX removing product without success. I am trying to do that because there are hard water spots that I just cannot remove no matter what I do, so I assume that there is RainX or some other "polish" covering them. Any suggestions??
Have been using Bon Ami for lots of things for years, it's a polish, not a cleanser. In the owner manual for the 72 Chevelle I used to own GM said use Bon Ami to clean glass.
Used RainX years ago when it first came out, loved it in the pouring rain but found once applied it was all but impossible to remove it permanently from the windshield. You could always see where the wipers tracked when you washed the car. When a new windshield went in that car I never used it again. Bob
Years ago at the local auto glass shop, which is now out of business, the son gave me a tub of Cerium Oxide in paste form to remove a scratch in a side window of my daily driver. Using a felt wheel and making sure you don't heat the glass it did a very good job. Would think it would be killer for water marks. Bob
if no good result yet, try mister clean with ammonia, that should cut though any crud. If not good progress with the previous treatments, try CLR (calcium/lime/rust) remover, available at most supermarkets, Home-Depots, it should cut through any stain without leaving a trace. HTH