Audi A8 Transmission Service

My car, a 1999 A8, has 75,000 miles on it. I bought it with 70K.
Considering the state of the spark plugs, air filter, and other
components, I assume that the transmission fluid has never been
changed. Since a new A8 5 speed tiptronic transmission costs
about $8000, I decided that a fluid and filter change was in order.

I have the Bentley service manual for the car. The procedure
sounds easy enough:

1. Open drain plug and let fluid drain.
2. Remove transmission pan bolts and remove pan.
3. Remove filter (screen) bolts and remove old filter.
4. Install new filter
5. Install transmission pan
6. Remove fill plug and add new fluid.

Of course, the procedure is a little more complicated than that.
With the help of the friendly people on AudiWorld, I was able to
do all the work.

Here are some pictures and some hints.

The victim ready for  work. Note that the car should be level for this procedure. If not, you can't
properly fill the transmission.

These are the parts you need: pan gasket, new screen, and super special VW / Audi
transmission fluid (at $12 -15 / quart, you should buy 8 quarts). Remember to also
buy new crush washers for the drain and fill plugs (I didn't and if the originals leak
I will be very mad).

This is the transmission pan. The small bolt is the drain, the large one is the fill.
The bolts are Torx bolts, size T-27. Why Torx and not Allen? Why T-27 instead of
the more common T-25 or T-30?

The fill plug is a 17mm Allen. Make sure you can remove the fill plug before you open
the drain plug. You don't want to drain the fluid, then find that you can't fill it! I tried using
two 17mm nuts welded to a bolt with a 17mm head. No good. The fill plug took a lot of
torque to loosen. I had to buy a 17mm L shaped allen for $9.00. I put a 2' pipe on the end
and it came right out.

Different shot of the transmission pan. Of course, nothing can be easy. Note that two
bolts are obstructed by the catalytic converter. You could remove the exhaust, but that
would be a real pain. Instead, buy a Torx T-27 bit from Sears. Grind off about 1/4".
Lock it into a vise grips, and you can use that to loosen the two bolts. I also recommend
you have a socketed T-27, and a screwdriver type T-25. You can use the T-25 to remove
the two obstructed bolts. The smaller tool allows you a better angle into the bolt. Be careful
to not damage the bolt head too much.

You need a socketed T-27 to torque the bolts when you re-install them. It's also a lot faster
to use the sockted tool than to put the bit into a 1/4" socket. The bit will fall out and you
will waste a lot of time crawling around the floor trying to find it.

Make sure you can loosen the two bolts before you drain the fluid.

This shot shows the trans fluid draining. Be prepared for about 6 quarts to drain.
Note that the Audi fluid is not red like every other trans fluid. It's sort of yellowish
green. Mine was in much better condition than I anticipated. It was still clear, not
burnt and did not smell rancid or overheated.

Note the two obstructed bolts in the top right.

I was surprised that when I removed the fill plug, a lot of fluid came pouring out.
Fortunately I had the drain pan positioned. I learned that when the engine is
running, a few quarts of fluid get sucked out of the pan into the transmission.

The fluid is drained, and the pan is off ! There is a good amount of sediment in the
bottom of the pan. The four small rectangles are magnets to collect any steel particles.
Mine had some sludge on them, but it appeared to be normal wear.

The parts manager didn't think it was necessary to change the fluid, as Audi describes
it as "lifetime". Considering the amount of sediment and sludge present , I disagree.
Many people on Audiworld have been recommending changing the fluid at 30K.
From what I saw, that may be too often (especially at $60+ for the fluid). If I still have the
car, I would probably change the fluid again at 150K miles (another 75k miles).

The filter is still bolted to the transmission with two bolts. Remove them and it comes
down. Note that there is a rubber o ring on the output of the filter. Note that those
two bolts are different than the trans-pan bolts (shallower head).

The filter has been removed. Here you can see that it is also covered in sediment.

New filter and old filter. Which would you rather have in your car?

Nice clean plan. I used oil eater type stuff, then some rags. Follow with a wash of
brake clean, and finish with paper towel.

Clean pan, drain bolt installed, gasket placed. I use a dab of vaseline to hold the gasket
in position until it can be bolted in place.

Next I positioned the pan and bolted it with three bolts. Make sure the gasket is
properly positioned and insert the rest of the bolts finger tight. Then use a cross type
pattern to tighten each bolt to 7-9 ft. lbs. You won't be able to torque the two bolts
above the cat-con, so just make those snug.

Now came the hard part, filling the fluid. For some reason, unlike every other car I am
familiar with, Audi does not have a transmission dip stick / fill tube. Instead, the shop manual
tells you put a special hose into the fill hole, and add 4 quarts of fluid. I don't have the special
tool, so I bought a cheap pump from Harbor Freight (

One end went into a quart of transmission fluid, the other into the transmission. Then it
was just a matter of pumping the fluid it. Of course, the hose in the transmission did not
want to stay in there. It took some time, but I eventually filled the pan. The shop manual
instructs you to fill the pan until fluid run out. Then start the car and shift through all the
gears, staying in each gear for 10 seconds. Then, with the car running, pump in more fluid
until it runs out. That took me some time, and I probably pumped $10+ of Audi trans
fluid onto my garage floor. When you have filled the pan, put the plug in before you turn
off the car. Otherwise, fluid will pour out of the fill hole when you turn the car off (don't
ask me how I know), and you will have to pump more fluid in.

A better way of filling the trans would be to make a hook from copper tubing or something
like that. Then the hose won't fall out and you won't waste much $12 / quart fluid.

Clean up, lower the car, and enjoy the ride.