Hi, I was running along this thread, and I could not find a discussion on this thought point :-
Car exterior includes Black Plastics and Trims
also and you can find one just below the Windshield glass also. The wash-off from the windshield flows on to it and drains through the hole on this Trim.
Your car would lose its stock freshness and look very much ugly and old if this Trim becomes grey or white.
Hence be careful when using Hair shampoo or similar substances including Tooth paste! (I read this suggestion somewhere else and not in this thread). Long term use of this may lead to graying of this trim!
I also have experience of graying of Trim, due to careless usage of Wax polish on the Car! Had to go for Dashboard polish, I got one which is manufactured by Pidilite industries, it was effective.
Anybody thought about this?
Now I feel that for windscreen, 1) we shall use cleaning liquid available for Mirrors/Glasses, 2) The substance must be mild and not powerful...