Frank provided this tip, “I’ve worked in Chevy dealers since 1971 and they used to carry Windshield Cleaner, Bon Ami cleaning powder part # 1050011. It was mainly used for windshields that had oily or greasy film on them from wax or what have you. It works very well (I’ve used it myself) just follow the instructions.

It may still be available at GM dealers. I still have a box at home and the seal on top reads ‘same formula as Bon Ami cake’. Now you would think that Bon Ami cleaner available today would be the same since there are no bleaches or chemicals listed in the ingredients. But the container reads ‘do not use on windows, glass or mirrors.’ Very puzzling….”