To Change or Not to Change (ATF): What's your experience?
 

So, I have some imperfect behavio(u)r on my 150k-mile A8L. Sort of flares/slips a tiny bit, mainly when cold. I do have some codes, below, (brake light switch; and ABS, which I think is related to the BLS) which I will clear to see if they recur, and replace the BLS, but what is everyones' experience with changing the ATF? Is there a way to determine the current SW version in the trans, short of the $tealer $ervice dep't? Can I tell which (blue or yellow) fluid is in there or could it be brown enough to obscure its original colo(u)r? TIA for any empirical evidence!
-Tom
Here are the most likely codes; I'll posted the whole scan in test forum <link> .
Address 02: Auto Trans Labels: 09E-927-156.lbl
Part No SW: 4E0 910 156 E HW: 09E 927 156 A
Component: AG6 09E 4,2L5V USA 0060
Coding: 0000002
Shop #: WSC 02353 785 00200
VCID: 24475AF8E7C0DE3

1 Fault Found:
17087 - Brake Switch (F)
P0703 - 000 - Electrical Malfunction - Intermittent
Freeze Frame:
RPM: 640 /min
RPM: 192 /min
RPM: 32 /min
(no units): 7.0
(no units): 34.0
Temperature: 70.0°C
T.B. Angle: 0.0°
Voltage: 13.92 V


-------------------------------------------------------------------------------
Address 03: ABS Brakes Labels: 4E0-910-517.lbl
Part No SW: 4E0 910 517 A HW: 4E0 614 517 E
Component: ESP 5.7 allrad H29 0420
Coding: 0007597
Shop #: WSC 03419 000 00000
VCID: 214953ECF8D2CBB

2 Faults Found:
00526 - Brake Light Switch-F
011 - Open Circuit - Intermittent
00526 - Brake Light Switch-F
008 - Implausible Signal - Intermittent

The F-125 switch issue is documented on Audipages HERE and Adrian_E had the issue on his car HERE - take a look. +++

I also changed ATF at 60,000miles and again at 120,000 miles with no ill effect. (Vote above only allowed me to select one ATF change.)

That fault code is for brake switch not F125. It is normal to have it. If you press brake pedal after switching ignition on and before rumning scan it will not appear.

If your box is at the start of problems, then go for it and see how it behaves. I've had both my D2 and 'previous' D3 done, and it's kept them trouble free.

Sealed for life was something the manufacturers came up with in the late 90s. Before that torque converters had a drain hole to allow all the contaminated oil to be drained out. During 2000-2005 they still insisted that the boxes were sealed for life, but suddenly around 2005 they changed their minds and put the ATF on the service schedule as a one off change at around 40k. The reason for this was they were getting too many warranty claims for faulty boxes, a much higher percentage than before the sealed for life box was 'invented' and further investigation revealed that a single change at 40k removed all the crap that was inside either due to manufacturers leaving a tiny piece of swarf in or through normal wear and tear.

I personally like to change the ATF and filter, then every couple of years change the ATF only, not a big job once you have done it a few times, and from what I've done they all seem to be of a similar system and roughly the same procedure.

I've read that some people change the ATF and then experience problems, but I would be asking if there were any problems before the oil change.

The oil through time becomes contaminated and the filter choked, I can see no good reason to leave it pumping around inside the box, best change it and keep it fresh

no not there but the full scan he did HERE did. . . +++

I had similar behaviour from my cold box and had brake switch errors - also it sometimes seemed to be in the wrong gear when exiting a roundabout.
Changed the switch - £10 part - and 20 mins (by the brake pedal) and all seems ok now.

Thanks for the replies. I have the switch ordered, will keep you posted :D

The switch makes a huge amount of difference on the ZF6HP. Especially at low RPMs.