I've had some success with sunflower oil on window rubbers. Seeps into the gap and then polymerises slowly.

I'd doubt a 53 Beetle would have glued-in windows, though I don't know that for a fact, and that "The Works" stuff is supposed to work with rubbers too, and its supposed to work in the wet.

Sunflower oil works best if applied when its hot, dry and sunny, though, which might be difficult to achieve in the UK right now.

Clean it off the glass sharpish. Goes sticky fast

Edited by edlithgow on 02/03/2013 at 10:39