According to Bentley, the spark plugs are good for 48,000 km. 
(They're either NGK or Bosch, installed by dealer a year ago).

I'm wondering if it is safe/recommended to pull the plugs at certain 
intervals to check for wear,oil, etc? Or should I just wait until the 
48k or when it starts to run poorly, to avoid extra wear on the 
aluminum threads?

It's now been about 16k, and I'm debating checking/replacing plugs 
before leaving for a 3000km trip. It has a slight, occasional miss at 
idle when engine is hot, but seems fine otherwise.

Shawn & Janis Wright
'88 Westy (338k) '85 Jetta TD (375k)
VWnut@smus.bc.ca  :  swright@smus.bc.ca
http://www.islandnet.com/~swright/vw.html
http://www.smus.bc.ca