Yet another issue I had to deal with is water spots on windows. While this seems like a trivial problem, it turned out to be anything but as these are the water spots from hell. I initially washed the inside and outside of all the windows thinking it was just built-up grime from sitting outside for a year. That improved things greatly, but upon closer inspection, the water spots remained. I’m assuming the build up of grime and the almost daily rains and intense sunshine created these spots.
I subsequently scrubbed them with a bug pad and SimpleGreen, then a Scotchbrite pad and even tried to scrape them with a razor blade. None of these efforts had any effect so I dug into some Internet searching to see what I could find. It turns out a polishing powder called cerium oxide was the answer. When mixed with water into a thick paste and used with a felt polishing pad on a drill, cerium oxide will remove impurities and light scratches from the glass surface.
For my first attempt using cerium oxide I polished half the window on the passenger side of the extended cab. I did four separate applications, each with increasing pressure, where I went over the glass a half dozen times or so. I was concerned with just how abrasive it was so I started fairly light. Based on this first experiment, I can be much more aggressive with the polishing and probably accomplish the same effect in one or two applications.
The finished result was impressive and appears to have restored the glass to factory-new condition. Now I just have all the other windows to do, including the windshield.
Update 2/14/22
I used an optical grade cerium oxide as opposed to “regular” cerium oxide that is used in lapidary (rock polishing). I should also stress that I was not recommending cerium oxide as a glass cleaning method for regular dirty windows. I would suggest exhausting all other cleaning methods before resorting to this technique as it is messy and very labor intensive.