has anyone tried cleaning the windshield with Bon Ami 1886 formula? I have a film on my glass that is either from road grime or from the silicone wiper blades but it wont come off with windex or soap/ammonia. I read that BMW suggests cleaning their windshields with this Bon Ami powder and water. I have heard of glass refinishers using extremely fine steel wool but im not going to try that.