Something I learned by making a mistake first: Paint overspray on windshield and rest of truck. I clay barred the overspray off the paint, and it did a great job, so thought "Why not" on the windshield. It worked perfectly! So clean that I took my service van to the car wash and clay barred it's windshield as well. You would not believe the black road...uh...'stuff' that comes off with the clay bar!!! Just keep it wet like you do on the paint. You can FEEL when it is clean...nice and smoooooth!
P.S. The 303 stuff is great! You can also find it at R.V. places like Camping World, and once in awhile even WallyWorld has it in the R.V. area.
MCTOY