My Renault Clio II has a very streaky/greasy windscreen. It's only apparent in a couple of spots on the glass, but glares in the rain at night. I've tried everything from wipes to sprays and it just won't shift. I'm not very comfortable with driving at night now due to the restricted vision when it streaks.

A friend of mine suggested baking powder and a damp cloth - I suppose as a mild abrasive this might help, but I would like some consensus on this.

What do you recommend to shift a smear that just won't budge?

  • On a similar vein to baking powder, I've heard toothpaste suggested - probably for the same reason. I've never tried it myself though...
    – Nick C
    Commented Oct 30, 2014 at 10:45
  • Is it just smears, or are there actual scratches in the surface of the windshield? If just smears, you need to clean the windshield with something which will cut the goop, and then you need to replace your wiper blades with new ones. Commented Oct 30, 2014 at 12:56
  • Is the dirt on the inside or the outside? Does it come off if you scratch it with your fingernail? What if you rub it firmly with a dry cloth or paper tissue? (I find that it's easiest to see/clean windshield dirt in the morning or evening, when the sun shines directly on it at a low angle.) Commented Oct 31, 2014 at 1:50
  • It's strange because there isn't actually a mark as such on the screen. In dry weather, it's crystal clear, it's only when it starts raining that it becomes apparent. It's not the wipers, as I replaced those and the spot was where before and after. I have tried the baking powder, which I have not had a chance to test yet because it's not rained. The car is going in for a health check on Wednesday so I'll mention it to them then.
    – James Hyde
    Commented Oct 31, 2014 at 13:29
  • I'd avoid an abrasive. Try some wash'n'wax in your wiper wash bottle - say a cap full every time you fill it. It will clean your windshield of oils and leave a layer of wax to keep oils off it for a while. Rain then tends to bead and run off your windshield all by itself. Commented Nov 6, 2014 at 6:01

2 Answers 2


The first thing I would try to do is use a very good window cleaner, or even vinegar. Just get it as clean as possible.

Assuming you already tried something like this, the next thing I'd do is use a clay bar to see if it will pull the contaminants off the windshield. Use it just like you would if you were cleaning your paint job.

If the clay bar doesn't do the trick, try using a product like Detailer’s Pro Series High Performance Glass Restorer. A product like this is non-abrasive and will not mar the glass. I would not use the baking soda. Even as light of an abrasive as it is, it is still an abrasive and could cause further damage to your windshield. While you can use other products to buff out a windshield with damage you cannot feel with your finger nail, it is a lot of work and is usually best left to the professional to accomplish correctly.

(NOTE: I am not promoting any products in the link or the link itself ... these are just examples of what I'm talking about.)


Old news paper used dry works surprisingly well. As does ultrafine grade wire wool (0000 grade) - don't use any other grade as it can damage the glass. White vinegar used on paper towels also is excellent at clearing glass.

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