On 18/11/2019 10:56, Harry Bloomfield wrote:
Tricky Dicky explained :
The main cause of judder and resulting noise is car washes both
automatic and hand wash. They apply liquid wax in the final rinse
which might make the rest of the car look nice and shiny for a while
but buggers up the windscreen. It might be OK with a downpour but is
notable in light rain when it just causes smear. My cars never go near
a car wash and it's years since I experienced any judder.

+1

When I have needed to fix it, I just apply some washing up liquid and
plenty of water..

Newspaper also works well.

--
Adam