I had about 7 or 8 nasty vertical streaks on the rear window of my 2010 RX 350, possibly from wiper fluid or hard water, or maybe tree sap. The marks were consistent with having used the rear wiper washer.

Anyway, scoured the 'net to find a solution and ultimately used glass ceramic cleaner which worked like a charm. HOWEVER, I saw a few posts suggesting a razor blade - similar to scraping paint or other grime from home windows. I tried that in one spot on the window, but it damaged the tint slightly - the area where I used the blade is slightly lighter than the rest of the window. This surprised me for two reasons: I've done this lots of times when painting windows frames - i.e. using a razor to remove spots on the glass - with no problem; it's baked in factory tint, not a film.

The mark isn't particularly noticeable to anybody who doesn't clean the car, and I wouldn't call it a scratch per se as light shines through it no problem. In fact it's quite tough to see on the inside of the vehicle, but under bright sunlight I can certainly notice it outside the vehicle. What I'm saying is most people wouldn't notice it BUT I KNOW IT'S THERE!!

It's probably not worth worrying about, but I'd love to know if there's an easy fix that won't make the problem worse. Has anybody had this happen, were you able to fix it, and if so how?