I tried the Rain-X additive. No streaking, the rain drops beading up just as advertised. However It did leave a film on the windshield which did turn into almost completely opaque when the sun is low and shines through from certain angle. It looked like a layer of crystalized salt. When this happens I need to sit up or down a few inches to change my viewing angle so that I can see again.
For this reason I stopped using it after it ran out. It took a long time for the residuals to go away.
For this reason I stopped using it after it ran out. It took a long time for the residuals to go away.