My windshield been in for 20 years and I washed it few times recently no carpet in car no heat/ac under dash bone dry not one drop. Wasn't looking to save money on sealant or half *** either. I looked at channel drains looked at how smooth my channel was new rubber seal soft pliable didn't see any need for any sealant. Got lucky it worked for me. I am sure your glass guy who does it every day knows way more then me ect ect ect...