trans oil

i also run D4.

I am of the same mind as Mav - it seems people use different stuff just to be different. use what was meant to be run in them.
 
also make sure you remove the fill plug first (before draining). otherwise you can end up with an empty trans or not know exactly that you have it filled to the proper level (and wont be able to check the level in the future). :)

good luck.