Source: AudiForums

This was done on a 98.5 30v 5 spd audi a4

it wasnt hard if you can change oil you can do this
you will need a special bit because the drain plug is tamper proof, i got mine at www.germanautoparts.com
it was a bit expensive ($25) but it is needed and it will work on both the drain plug and the filler plug.

first off drive your car around untill the fluid has heated up, this will allow the fluid to drain easier.

jack your car up

here is the special bit, along side the drain plug and fill plug.

un screw the drain plug and wait till all the old fluid has trickled out
heres where the drain plug is, its right on the bottom of the tranny, you cant miss it

replace the drain plug and remove the fill plug
the fill plug is the large bolt in the middle, it is on the drivers side of the gear box near the axel

i used mobil 1 75w90, fully synthetic, this is what the manufactuer reccomends and it took about 3 quarts

you will need some sort of way to get the fluid up in to the filler whole, u used this pump type of thingie, you
can get it at any auto parts store.
pump it full.

the tranny will take more than 3 quarts but this is only because the car is jacked up and at an uneven slant, again only add 3 quarts

as you can see i needed this

and now my shifts are smoother than ever

torque listings

fill plug=18 ft/lbs
drain plug=26 ft/lbs