The day I bought my TSX, it had rained all day. I thought the marks on the rear window would clean off easily. I was wrong. They turned out to be permanent stains.

I tried to remove them with glass cleaners, clay bar, polishing compound, diluted vinegar... Nothing seemed to work that I could think of. I didn't want to scratch the glass with anything harsher. I also didn't try the orbital polisher to avoid scratching the glass.

I searched the web and found a site for Spot-X Hard Water Stain Remover that claimed it could remove these stains. At this point I was considering getting a new rear window, so I thought I would give it a shot for under $20. The results are pretty good.

In the pictures below, the driver's side of the rear window was cleaned and now looks like normal glass. The passenger side shows the blueish water trails and stains that were covering the entire rear window.

If you try to use Spot-X, it will take a lot of scrubbing to remove the stains. I got through about half of the rear window in 45 minutes of constant scrubbing action, but it is working.

Before:



After: