Have been skimming this thread waiting for someone to post '1z Gummi Pfledge' it is the cure for squeaky door seals:
http://www.1z-usa.com/einszett_gummi_pflege.html
Also, do not wax the door jambs and never put silicone on the rubber door seals.
Another good product is AutoGlym Rubber and Vinyl care.
http://www.autoglym.com/enGB/product...l.asp?v06VQ=HE