Gearbox crunch when cold

When I first run my Cabby from cold, it crunches from first to second unless I let the revs drop real low.  This does;t happen at any other gear change, and cures when the engine is warm.  Any ideas?  Cheers.

Pretty standard on a 020 VW gearbox. You can try and replace the oil with some semi-synth 75w90 to see if that helps.