The main purpose of the sealer is to keep moisture out of the joint between
two panels so that rust doesn't get started and rot out the panel joint.
Based on the evidence, I'd have to give VW a 1 or 2 out of 10 on the how'd
that work out scale. When I repainted mine I sealed over the old sealer and
the cracks came back. I guess the old stuff has to be taken out completely
before the seam can be resealed.  I wouldn't leave it out completely as this
only invites more problems.

Tom Smith
83.5 Westie