I use a ceramic spray on from Girots Garage that I pick up at O'Rilley's. It is impossible to spray this on and not get it on your glass. The good news is it not only works great on the car's paint but also on the glass.

It will not repel water like Rain-X, but it will clean your glass like nothing else and leave it clear. It will not repair the sandblasting from years of use.

I tried everything to clean up a windshield on a Toyota Landcruiser. Nothing works except for a new windshield.