Washer bottle soap

[whitey66]

Now to figure out the best way to keep those annoying spiders out of the mirrors.

Insect surface spray is great for this.
Get the can with the extension on it like this -
It makes it easier to spray in the gap without getting it all over the mirror and housing.
Don't spray too much or it will drip out of the bottom, this lasts for several months provided you don't wash it off when washing the car.

[technoweenie]

Usually ~$2USD...