The anti rain products cause "chattering" as the product wears off.If you use the stuff the first time they chatter is the time to re-apply;);););););).
They do stop chattering once its worn off.
D4 has been good,I use Rainex,D2 I gave up on Rainex.In the past Ive used in on various Falcons,Ford cannot make a window wiper:(:(:(:(:(,it helps but you have to keep the rain product up to the glass.Even the Territory has shocking noisy poor wipers:(:(:(:(:(:(
Andrew

