2005 CDI - 193,000 miles on factory ATF
 

Yes that's right, 193,000 miles, and the ATF was not changed in that time. The lockup clutch had a slight amount of shudder when I bought the car, and the red tab on the trans filler tube cap was intact. I suspected the fluid had never been changed, so I ordered up a trans kit from our sponsor. I also got two gallons of MaxLife synthetic ATF, and went to a friends shop to use his lift to change the fluid. My suspicions were correct, in that the fluid was greenish-brown. I did the same job on my previous CDI, and it had a worse shudder condition that a fluid change almost completely fixed. A dose of "Shudder Fix" (friction modifier) cured it completely. I was able to remove about 7.5 quarts from the trans using compressed air through the left side trans cooler banjo fitting (bolt removed). You can see the color of the fluid in the second photo, on the bell housing. After filling the trans, and taking it on a test drive, it shifts butter smooth.

Did you by any chance check the condition of the filter? It's stories like this that tempt me to do regular fluid changes but only do the filter once in a great while.

Not sure why anybody wouldn't change the fluid.. So dumb. The fluid gets thin with age and just doesn't lubricate the clutch packs and every other moving part like it should.

I did not, but like the last one, it was an MB filter.

These transmissions were advertised as "sealed for life", so no fluid changes were recommended. Yes I agree, that is dumb. However, looking at it from a manufacturer standpoint, they must feel that the "life" of the 722.6 is only about 200,000 miles. Most shops would suggest a rebuild for any problems like clutch shudder or shifting. One good thing on the transmissions in both the CDI's, is that very little grey fuzz (metal) was found on the magnet in the bottom of the pan. I suspect that this trans will last another 200k if it is taken care of. Had it not had the fluid changed, it would have surely gotten worse in a hurry.

Consider driving for a few weeks and doing another fluid & filter change. I've found that friction material will coat the insides after that many miles, and the fresh detergents in the new fluid clean it off. I.e. the new fluid may turn very dark in short order.

Same thing for diffs and manual gearboxes. I once bought a VW that I believe had 35 year old fluid in the gearbox. I changed it three times in three weeks and each time the clean new fluid came out a dark brown/black. After the fourth fill and drive, it finally came out clean.

I did consider that on the first one, but thought I would wait at least a few thousand miles and then have a look at it. I will probably do the same on this one. I was able to get most of the old fluid out, so I am confident it will not be too contaminated.

It would have been interesting to send that fluid out for oil analysis. I bet it's not as bad as it looks.

I bought a chevy pick up once (used) and the fluid was actually black. Like used motor oil black. Remarkably, the trans shifted OK. The truck had over 200K on it. I changed the fluid and ran it another 60 before I sold it. Needless to say, it shifter MUCH smoother after I changed it.

I'm not sure about MB, but I've heard they use a special wire mesh filter on many of the sealed transmissions.