An adhesive silicone with urethane blended in should be good enough for passenger window. No silicone will adhere as well as pure urethane though so if you want to be 100% sure the driver's side will hold, go with pure urethane like Goop, E6000, etc. Marine Goop is even UV stable but since it will be down in the door you don't really need that. Silicone is great for RTV gaskets and pretty good as a sealant too since it's UV stable - but it's a terrible adhesive. ...