My newly purchased '85 Westy has door locks that will work from the 
inside but on the outide you can't get the key to go all the way into the 
lock. I was told by a locksmith that VW uses heavy grease in their locks 
and to just keep squirting WD-40 into them untill they freed up then use 
a good lube spray.  I have tried this several times-no luck. The only way 
I can lock up is to lock the two front doors & slider then crawl through 
the back hatch and lock that (thaat one works!) Not a pretty sight!
Any suggestions?  (Was always parked near salt water)