Weather allowed me a good car detailing day today and after getting the exterior and interior clean, I tried using some cerium oxide polish on the front windshield to remove these annoying, fine wiper scratch marks. I got about 1/3+ of the windshield done before it got too dark, but it seemed to work well!
It definitely took some effort, but after taking for a spin tonight and I think it made a huge improvement! As I ran out of daylight, I'll do the drivers side and center tomorrow.
I used
CarPro "ceriglass" brand cerium oxide cream and
5" rayon pad on my
harbor freight dual action polisher.
At a speed setting of 2-3, I found it didn't sling any stuff around. I had the the rubber windshield gasket and trim taped off to protect those items. Probably about 3-4 times per zone I was polishing, I would add a bit more cerium oxide cream, and mist some water spray on the area being polished and the pad, to re-wet the drying polish, and keep going. I did press down pretty hard, (this rayon pad is pretty thin, and hard stuff - kind of like very stiff, dense felt) and it vibrated quite a bit. It was a good bit of effort! I found the 5-1/4" pad size had a perfectly matched radius to the curved upper corners of the Boxster windshield.
One thing interesting is I have Aquapel on the front windshield, applied probably 1-2 years ago, and especially compared to where I polished the glass with the cerium oxide, it was a night-and-day difference where the old Aquapel was - still beading up water, too! Although not quite as nicely as I remember after being fresh applied. (I've been really happy with the Aquapel treatment, plan to reapply a new Aquapel treatment after I've got the glass polishing completed.)