[Redd]

Rain-X is crap. Difficult to apply and doesn't last long.

That said, I've been using rain repellent on my car windscreens for over 10 years, 7 yrs on the M3, and have never had any problems with the sensors or wipers - no streaking, no juddering, no noise and no wear on the wipers. It rains year round here so the wipers get used regularly. I use Glaco Ultra (small black bottle) made by Soft99. 10x easier to apply and lasts much much longer than Rain-X. The only time Rain-X performed better than Glaco was when it was freshly applied in light rain/drizzle. Glaco needs a slightly larger droplet size before it slides/blows off. Long term use, Glaco lasts a whole lot longer and remains more consistent during that time, whereas Rain-X performance drops off quickly within 1-2 mths.