
Hi, May I suggest getting a clay bar use it with window cleaner (as the usual clay bar lubes will make your windscreen oily and a bugger to clean.) You find what the cause will be is more than likely some sort of industrial fallout, weather it's overspray or just a build up of road grime the claybar will usually take it straight off. If that doesn't work you can also use a FINE grade steel wool then follow it up with the claybar, neither will scratch or damage your windscreen. I have been doing my windows like this for the last 10-15 years as it works an absolute treat.
Cheers
Damon

Both Brad and I have had new windscreens fitted on our MPS's from Obrien's glass, both downright dangerous in the wet, smeared badly.
I used Rain-X to clean and coat the windsceen a few days after having it fitted on a trip to Wagga as I was so peeved with the visibility through the new screen. Worked wonders, I have re-done the screen with rain-X 3 times over the last 18 months. Still with original blades and it stll wipes perfectly with no streaking or smears.
So convinced I use rain-x on the vintage cars - hand operated wiper on 1924 Dodge hardly needs using. The "prince of darkness" LUCAS wipers on two of my other cars have a tendency to stop working at the wrong time so the rain-x is a great help.

the best thing i have done for mine when it is like that is a little cutting compound then wax it once youve dont that it'll be like new!!
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