body sealer

[RICH MUISE]

TIP: When you purchase the strip caulk at a paint supply shop, open the lightweight box it's packaged in to make sure it hasn't been crushed. I needed some on a Saturday, got there just as they were closing. He had one box, I bought it and went home to finish the windshield installation with it. Apparently they had stored it under something heavy and the stuff was all squished together...useless for the small strips I needed. I wasted lots of time making small strips from all that stuck-together stuff.
I have also used the roofing sealer strips that Pat mentioned....not on my car, on my garage roof that I redid a few years ago. light beige in color, about 3/8 diameter, much stickier that the strip caulk. I wondered how it would work for cars, figuring being for metal roof overlap seams, it had to be heat and cold resistant and remain flexible forever....now I know.

[gasman826]

I keep a roll of the black, butyl stuff and the light color 'plumbers putty' like stuff on the shelf.  I use it for both sealer and anti-squeak/rattle.  It also works to seal and cushion painted sheet metal joints.  Helps keep the paint from cracking/chipping.