I’m sure everyone has their own favorite brand of water repellent.
@Paul Iddon How has that stuff you’ve been using working out?
I’ve been using Rain-X since 1993.
I apply 3 coats on every piece of window glass, (front, rear, all side windows).
It lasts about a month, which is fine because it doesn’t rain that often in my region.
Here’s highway test footage of my 2010 Mercury Grand Marquis with a 4 channel dash cam, (two Viofo A129 Plus units).
Please forgive the lens adjustment, this was before I learned the importance of 50/50 road & sky.
By sheer coincidence “November Rain” just happen to be playing the radio while I was channel surfing. Lol
Here’s only the rear window;
Here’s road testing Rain-X vs. Nu Finish;
Here’s what the angle of my windows look like;
@BlackboxMyCar sent me some of these for test & review;
https://www.blackboxmycar.com/products/aqua-shield
I can see how these could be a life saver in the rainy / snowy Pacific Northwest.
For my application where it rarely rains I prefer to use Rain-X.
-Chuck