A6Gary

Even though I had no shifting issues, I recently serviced the transmission on my 2006 A6 Avant after 109,254 miles. Through that experience, I have some recommendations to assist my fellow A6 Quattro owners who are considering a DIY transmission service:

1. Verify which transmission oil pan is on your tranny. There are two types: one with 23 screws and the other with 13 screws. For the 23 screw pan, the replacement gasket, which green and non-metallic, is P/N 09L-321-371. For the 13 hole oil pan, the gasket is metallic and the P/N is 09L-321-371-A. My 2006 A6 had the 23 hole version.
2. You will need to determine which ATF will work will your transmission. Since the software in my tranny was never updated for the original, the recommended ATF per ZF was Lifeguard 6 or Lifeguard 8, so I purchased 6 liters of Lifeguard 6 to match the existing fluid. There are other brands of ATF that are also acceptable for the ZF transmission.
3. The subframe cross-member has to be removed to access the oil pan. The four bolts that secure the cross-member are single use, so you will need to purchase four new bolts (P/N N-910-666-01).
4. It is also recommended to replace the fill port (P/N 01V-321-376) and drain (P/N 018-321-377-B) plugs. For my A6, the O-ring seal (P/N 01V-321-379-A) for the large fill plug was discontinued per Audi dealers. However, it appears that the transmission version on the MY 2006 (build date late-2005) is an older version, so the seal may actually be P/N 01V-321-379, which is available. In any case, I used the original O-ring seal on the new fill plug.
5. If replacing the filter/strainer, the part number is #09L-325-429. Note that there will be additional ATF draining, so be prepared for additional fluid when the filter is removed,
6. To fill the transmission, you will need the angled fill pipe that can be inserted into the fill port. The AFT filling unit I purchased was supplied with several different filling adapters. However, the initial angle adapter I tried during the filling process was too short so it leaked and wouldn't fill the pan correctly. One of the other adapters did work, but it was slightly too tall to remove when the pan was sufficiently. This problem results in more fluid exiting the fill port. I would recommend that you obtain the Audi OEM adapter to ensure it works properly with the fill port.
7. Per the Audi Repair Manual, the temperature of the ATF needs to be between 35 C and 45 C (Not 30-40 C) for the correct fluid level.
8. The bolts that secure the 23 hole pan are M6 x 23 Torx head screws (they may also apply to the 13 -hole pan). Because the female Torx head may become stripped or damaged during removal (as I found out!), I strongly suggest purchasing some spares to have on hand. The part number for these bolts is WHT-000-747 (~$5/bolt).

I hope these notes will help anyone doing this DIY service.

G-Can

what are symptoms of fluid in need of replacing? thanks for the writeup. Love Audi and their $5 a bolt prices. Must be made of space station material

A6Gary

Although Audi Ag claims the ATF is lifetime fluid and does not need to be changed, ZF, the manufacturer of the transmissions, recommends changing the ATF every ~80K miles to maintain and extend the life of the transmission. Even though I had no transmission issues, the old ATF looked much dirtier than the new fluid, and the oil pan had some grime sludge it. There was also some minor metal particles on the two magnets prior to cleaning. Re: the $5 screws, yes, they are somewhat pricey. However, the MSLP for this screw is over $6 w/o shipping or tax.

A6 4.2 Vier

I have been replacing the trans fluid every 80K miles. Below are pictures of the pan (before cleaning) at 165K along with the fluid.

KevinGary

I get the ATF changed every 75k miles based on the recommendation of the transmission’s manufacturer.

A6Gary

That color of your ATF in the measuring cup is about what the color of my old ATF looked like.