Review on Enhance Your Windshield Cleaning with Rain-X White RX11806D Washer Fluid Additive-16.9 fl. oz, 500. ml by Brian Rivenbark

Much easier than trying to spray a window. The directions say 4 ounces per gallon of washer fluid, but I found I needed more. Might drop to 4 ounces with future refills, but we'll see. Works perfectly! I used it on a 2010 Subaru Forester and when driving down the freeway in moderate rain I didn't have to use the front wipers at all. The freeway speed was enough to keep the windshield clear.