While washing the car yesterday I noticed that there is great deal of staining on the windshield. It looks like simple watermarks, but I can't get the stains off. I've tried everything from window cleaner to rubbing compound on the inside and outside of the glass. Nothing even makes a dent in the stains. This stuff is so stubborn I can't tell if the stain is on the inside or outside of the glass. Thoughts?

 

Try a clay bar...worked on mine!

 

Sounds like water drops that have sun-dried on the car. Tap water from the hose will usually leave behind mineral deposits if not wiped down before the sun bakes it. So a clay bar works on them?

 

That's one of the reasons to dry your car after washing with municipal water supplies or any high mineral content water. I recommend plain vinegar to clean the glass. It does a great job removing water stains - DO NOT USE on bodywork (but I really didn't need to write that - DID I !? ! ) .

 

Good old paste glass polish works wonders with a buffing wheel!

 

Windex, kitchen soap and sponge works for me.

 

I have something more permanant......its like a line where the windshield wiper stops in the middle of the windshield. You cant see it when its dry but you see it when its raining....weird and annoying.

 

Exactly. The windshield can be polished with a buffer just like when working on the paint.

 

Why what does this do?

 

I would guess that it's on the outside. You could try a non-scratch abrasive cleaner like Bar-Keeper's Friend and a razor.