I don't think you can put all transmission problems down to "a few lemons in the bunch"

Stepping back, though, the problem with many of these anecdotes is that posters are continually mixing up the terms reliability, and durability. They are two very different things. If you want to improve a vehicle, you have to look at the causes of failure, not just the fact that it stopped running.

If the problem was durability, the issue would essentially be that the transmissions were wearing out. We would expect to see transmissions with hard use wearing out sooner, and the ones with light use (as posted above) would generally last much longer. In other words, there would be a relationship between how hard the use was, and how long the transmission lasted. Among other things, we would see fluid breakdown and failures related to a lack of lubrication. We would expect to see overheating, and burnt clutch plates. If these were the problems showing up, then changing the fluid or adding a cooler would be reasonable preventative measures to extend the life.

If the problem was reliability, the issue would be that the transmissions had random failures, for a wide variety of reasons. They would be at all different mileages, with little in the way of statistically-significant patterns. Some would fail as early as 10,000 miles (check). Some would run 200,000 miles on the original fluid (check). Transmissions would fail whether they had hard use or easy use, towing trailers or not. The fluid would often look good, even on a failed transmission. There wouldn't often be signs of overheating on a failed transmission, such as burnt fluid and burnt clutch plates.

It just seems to me that these transmission issues we keep hearing about are far more related to reliability than durability. Yet people always seem to want to apply durability fixes to reliability problems. That is illogical.

Manufacturers would address reliability issues with more testing, with fewer product changes over time (more stable product), and with simplification. We all know how BMW feels about simplification. Why have a five speed transmission when you can fit a six speed or eight speed in there. Why have a mechanical linkage when you can use electronics for the same purpose. Why have a switch when you can have a micro-processor controlled signal. Why have a dipstick when you can have a sensor measure the capacitance of the fluid and its temperature, and then calculate the level. Etc, ad naseum. That complication breeds additional failure modes.

If it makes people feel better to change the fluid, they should do it. But I don't see why they would relate that to solving a problem of random failures that don't link back to a lubrication problem.

Maybe I am missing something, but colour me confused.

You have found and referenced a service manual page that recommends a transmission fluid change. You are promoting that fluid change. You claim that so far, everything is good.

But, on other threads, you detail out that you are using a non-approved fluid, and an aftermarket transmission filter. And now, after changing the fluid, your transmission is slipping whereas it wasn't slipping before you recently changed the fluid.

Is there not some inconsistency between your maintenance approach and your results? You may want to change back to OE fluid and filter, and see if that fixes the slipping. But if it doesn't, perhaps you should rethink the logic of changing the fluid so regularly, as it may not have helped you at all.

http://www.xoutpost.com/bmw-sav-foru...ge-tranny.html

Okay I don't know that the two are related. My problem with slipping is only when it is very cold like below 25dgrees and only for the first run through of first and maybe second. Once it runs for a while it runs like it was new.
So the responder that suggested it could be an aftermarket filter when cold is duely taken to heart. I think it is being starved for fluid at very low temps. a combination of out os spec filter and cold dense fluid... that's just a theory and I can't blame BMW for my error. My efforts are an earnest attempt to increase the life and of course my reliability of my transmission... so I can put of that rebuild as long into the future as possible. Don't we as high paying customers deserve both High Reliability and Durability?

as far as non-speced atf fluid my transmission is a GM. My dealer service department doesn't sell transmission fluid to customers. I asked what I should do. The service tech walked out side with me and told me they use any DEXvi they can get in bulk.
I asked him if Mobil1 trans fluid would work and he said it's one of the best for that transmission. Then he said you can use any Dexvi... all dexvi is synthetic.

I am thinking that my problem has to be related to the aftermarket filter which by the way is the second one of it's type that I put in there.I Probably have 60,000 miles on the same brand of filter with no problems except for recently in the very cold 15degree temps in the morning.

Apples and oranges. I will get a oem filter and put it on and let everyone know if it solved the problem.

To your first point. You can put a man on the moon and spacecraft out to pluto but, these German scientists can't build a tranny that is statistically reliable for as long as the engine can run? It wasn't that many decades ago that at 100K you were routinely rebuilding the top half of the motor in every day cars.
I'd like the same effort made on the trans... Think NEW PARADYME (sp)

I believe reliability can be improved and match that of the engine.

Someone on this board that posts far more than me and had data to back it up said that the transmission is the weakest link on these x5s. his data suggested to me anyway that other companies were building bullet proof transmissions... Honda, Toyota to name a few.

I don't want to start a race war here on MLK day but the venerable Japanese understand a thing or two about reliablity. my German ancestors would be turning in their graves. If they knew what we are putting up with just to drive this german car.

JCL, we all heard about that radial bearing wearing out and causing a failure. Could this failure be due to micro residues smaller than what the filter can filter, and act as an abrasive media inside the bearing and accelerate its wear? Also, these micro residues (if they exist) could interfere with the good operation of the mechatronic.?

I know that a transmission is a sealed system, but on hydraulic machines, that are also sealed, the hydraulic fluid needs to be changed in a maintenance schedule. What would be the difference between both systems.
I'm not arguing, just trying to understand.

The difference is the complexity if I understand right.As well as a human factor of screwing up the fluid level etc. Just my thought.
Some things work better and longer without you poking them unnecessarily.
When I bought my X,it was sitting for a while and what my indy told me was,that the ATF is a dark jelly now and when he drove it,it wouldn't engage the 2 gear for a second and slam afterwards.Bad ATF,sludge what eve it was causing it,I don't know.
SOOO,make it shorter.They drained half of the ATF and refilled with new,I have no idea which brand etc,I have no idea if the filter was changed at that point.
After 600kms my Torque Convertor started shuddering.
I had a tranny rebuilt.
Conclusion,If you service something make sure you do it right,and the only way to do it right is following the manufacturer's literature and specs.
It was my first Auto box and still is,I had no idea how complex they are and how sensitive they can be to fluids,filter etc.
When the tranny was already rebuilt,I had some Filter whining due to an aftermarket filter,Filter needed to be changed.
I was filled with Dexron IV ATF because it was the only thing the shop carried.It took me 15 liters of right ATF to get as close to the full volume of right specs fluid.
Torque Converter needed to be rebuilt twice...valve body was rebuilt,but didn't meet the specs and aluminum casting part was replaced...
Why I write all this?
If you tranny isn't giving you headaches and you flush it,at least Do It Right with right Filter and Fluid,I see absolutely no point of saving $50– 100 bucks and getting wrong stuff in.
Am I wrong?

If all the bearings in a transmission were worn I would suspect the fluid. If one breaks I would suspect the bearing itself.

I wouldn't worry too much about residues smaller than the filter takes out. That is the criteria for what size particles need to be taken out when the filter is designed in the first place

I think you are right. It is why I keep pointing out to Ghost that his non-Dexron fluid and aftermarket filter are high risk, and may very well be the cause of his engagement problems, apart from the discussion about changing them in the first place

I've been following this discussion and good to hear two points of view as I vacillate between changing the fluid or not from week to week. Oh, and thanks for posting the link to the video ghost, I LMFAO :thumbup:

Kinda off topic but related and I haven't found it discussed, but is anyone else noticing a change in transmission behavior with the AC on as opposed to off? With the AC on, my transmission shifts perfect with it off, shifts are noticably rough and I ocassionally get the 2 to 1 "lurch".

.
I am having a feeling this is due to the mounts wearing.