This article is from the VW Technical FAQ, by with numerous contributions by Jan Vandenbrande others.
A: "Lubricate" the door seals with Talcum powder or ClearGuard. "Lubricate"
the rest with ClearGuard or Silicone spray. You may also want to adjust the
doors so they close better by first loosening the strike pin and moving it
either in or out. The rear hatch lock can also be moved a bit, but it's
easier to adjust those black knobs on either side of the hatch. They screw
in and out.
 
Continue to: