This is the ultimate in 3M seam sealers. It's paintable, never shrinks, stays flexible and bonds to anything clean.
Winzer Products markets the same stuff. I've used them since the 90's with no failures. These are the only seam sealers that we use.


http://www.autobodytoolmart.com/3m-ultrapro-urethane-seam-sealer-gray-08361-p-10388.aspx

Steve