Windshield replacement

The factory recommended putting a non drying black mastic sealer in both the window side channel and body side channels of the rubber. I had a windscreen shop replace mine dry once and it leaked, plus they scratched the paint and it lead to rust in the windscreen frame. I had even left them a copy of the factory instructions which they obviously knew better than. Well I pulled it out and followed the instructions and never had a leak again. Remember the windscreen frame is not that smooth, spot welds, sheet metal overlaps etc., this is why they say use the sealer.