Okay, here is an easy one. My s40 windshield has some light diffuse scratches from using a set of old windshield wipers way past their replace date.

They are not sharp, but diffuse scratches. I have tried traditional methods to remove them. Using such things as windshield wiper fluid or windshield washer fluid. They do not work. What will work?

Newport_j

 

I did the same thing to my old 300zx twin turbo. The driver's side wiper blade was in such a poor state that it made a series of ground-out arcs across the part of the windshield where the top of the blade traveled.

The advice I got was to polish it with steel wool and water. This ended up being bad advice, because while it made the scratches appear less bad, in sunlight they actually looked worse from inside the car.

I then went to my local parts store and bought a "scratch repair kit" or whatever it was called. It was basically a sponge-type thing and a rubbing compound in a tube. That worked very well, for about 8 months before I started being able to see the scratch again. I got more rubbing compound, followed the directions on it, and the scratch was gone again. I assume this cycle would have repeated itself if I had held onto the car.

 

You can use toothpaste to remove some light scratches in the windshield. Put some on a rag and rub hard in a circular motion. If you can feel the scratch with your fingernail, it's probably too deep to get out with anything.