I replaced all the glass in my P15 awhile back. Had a local glass place install and used Steele's rubber. Bottom line is I can't even wash my car without some water getting into it. The worst place is the rear quarter windows, which do not fit tight at the body interface. Also a little gets through where water puddles in the lower corners of the windshield.
My cowl vent is also not watertight even with a new gasket. At this point, the interior of my car is pretty spartan. The back seat is out and I've got 2 coats of POR 15 on the floor, so wiping the water out with a towel is no problem. However, I'm getting close to finishing up the interior, and I sure don't want it wet.
Thought maybe after the car sat out in the hot sun a few times, the rubber would expand and seal, but no dice. Has anybody used 3M adhesive to finish the job? And what should I do about the cowl vent? Gasket came from Steele also!