There is not a lot of info about this on Tacomaworld so I thought I would share...
NOTE: If your windshield is at the point where you can barely see out of it from scratches and abrasions, replace it.
If there are some very mild scratches left from your wipers and general wear which is leaving almost a haze or very fine lines, then this just might work for you and will save you the expense from buying a whole new front windshield if it bothers you enough.
How Cerium Oxide works:
This works just like a polish that you would use on your paint. A polish or compound with mild abrasives that you would use on your cars paint will take off very fine amounts of paint leaving a shine. Cerium oxide works the same way by removing very fine bits of glass.
1) For my front windshield I used 4 oz. of Cerium Oxide which was just enough. Cost- Under $15. (See attached picture).
2) A felt polishing wheel. Cost: Under $3. (See attached picture).
3) A high speed rotary polisher. Cost: However much you want to spend.
4) (Optional) Spray Bottle (you can use something like an empty windex bottle).
1) Be sure your windshield is really, really, really clean and lift the wipers off of it.
2) Mix half and half Cerium Oxide and Water in a container. Meaning if the Cerium Oxide fills up half of the container, fill the other half up with Water.
3) Prepare your applicator of choice be it spray bottle or the pour method.
4) Prepare the high speed rotary polisher with the felt pad.
5) Pour/Spray a generous amount of the Cerium Oxide and Water slurry directly onto a 2'X2' section of your windshield.
6) Just as you would with polishing paint, spread a little bit of the slurry with your polisher and then start polishing. You will want to use moderate pressure. NOTE: DO NOT BUFF UNTIL THIS IS DRY. KEEP THIS LUBRICATED AT ALL TIMES WHILE BUFFING!
7) After several overlapping passes, spray down the windshield with water and clean it up. See how your progress is coming along.
As I said before, ALWAYS be sure that the felt pad is lubricated well with the slurry when buffing! Do NOT buff one section too much longer than another as it can cause distortion in the glass. You will both see and start to feel when everything starts drying up.
This process may take up to a couple hours to do it thoroughly. I hope this is able to help anyone out there with some mild scratches in their windshield. It isn't a lot of work, it is just tedious. Feel free to ask any questions!
EDIT: A word of advice- This stuff is VERY messy. Easy to clean off pain, but ohhh boyyy get it on some plastic trim and you have quite a bit of work cut out for you. Use protection if you know what I mean... I recommend that you cover the trim over the ENTIRE truck because it will spray everywhere. I was even finding this stuff in the bed of my truck.