I just finished a transmission and differential lube change.  I did the Redline thing like a good sheep following the flock.  :-) 
Anyway, I found a great way to get the lube into those dastardly fill holes.  But before I tell you that I wanted to say that I found a 17 mm 3/8 in drive "Volkswagen Drain Plug Tool" a the local Tool Town,  for $4.95.  I forget the manufacturer now but can supply it if its wanted. (They are some where in N.Y.)  Tool Town by the way has a great selection of Automotive specific tools, many for particular makes, for good prices.  Now for the oil fill trick.  Get a 6-8 foot piece of tube from the hardware store or otherwise.  3/8 to � in inside diameter works great.  Open the fill hole and insert the tube a bit.  Snake the tube horizontally across the top of the lower swing arm (transaxle) and out over the tire inside the wheel well.  Tape the tube down to something close to the hole to keep it from pulling out.   Now put a funnel into the other end and stand at wheel well and pour away!  The tube will be practically flat from the swing arm to the hole so when you pour from chest high above the wheel the oil has a direct shot into the drain hole.  Up front the same thing works.  There is a perfect shot at the fill hole from the wheel well.  Adding the red Redline transaxle oil with a funnel and clear tube  looks like you are giving the van a blood transfusion!    Try it, it works fantastic.
Bye 
Nat