We use this on all of our washes and on all windows. You can buy it here.
Long lasting shine and water beading on any exterior surface!

Renny Doyle Double Black Bead Maker Paint Protectant is simple to use spray on, wipe off paint sealant that will provide your paint with amazing protection, water beading, and shine for months! Renny Doyle Double Black Bead Maker Paint Protectant was developed using unique polymer protectants that are safe to use on any surface of your car’s exterior. Renny Doyle Double Black Bead Maker Paint Protectant can also be applied to any surface, whether it is dry or wet!