Let's talk Transmission Maintenance...

[ard]

Originally Posted by JCL

The service intervals have a baseline, and then are adjusted by things such as fuel consumed. They are also using sensors that directly measure oil condition now. This is all for engine oil change intervals, more than for other fluid intervals, as I understand it.

As I pointed out above, the latest X5 service guidelines state that CBS isn't used to compute ATF service.

I know of no specific "oil condition sensor". Generally it is based on total Liters of Fuel Consumed.

A

[ard]

Just beacuse there are people with over 100k miles on a tranny it is NOT proof that ATF service isn't a good idea.

(Indeed, my grandfather smoked for 50 years and was hit by a bus, therefore cigarette smoking is safe.)

The numbers of people drviing 100-150k mile BMWs is rather small, and therefore collecting coherent data from a sample like the internet is pointless. Indeed, the sum total of data we receive on trannies is "needs a rebuilt" or "I traded it in". We will not get details on failure modes.

Your comment about "fluid" being an independent component (ie fluid life longer than MTBF) is a bit off-the fluid is a lubricant for the mechanical assembly... you cannot consider it independently... Here is a analogy: why bother with changing motor oil? Afterall, we rarely read posts of people with 'failed oil', and the odds are that something else in the motor will fail before the motor oil fails...

There is no risk with doing a BMW recommended fluid service. You compare it to surgery- I compare it to a haircut.



Adam

PS thx for the pdf of the sensor.

[JCL]

You didn't ask for a fluid analysis, you asked for data that supports fluid lasting 100,000 miles. If that fluid has not caused a transmission failure by a significant margin beyond that 100,000 miles, then it seems a reasonable conclusion that the fluid has lasted. In the same day, we heard about another 40,000 mile transmission failure. That supports the MTBF hypothesis, ie that it is somewhat random.

Why bother with changing motor oil? Because it becomes contaminated by byproducts of combustion. If it was a case of it just getting dirty, we would just use better filters. Centrifugal spinner filters will clean the oil better than when it is originally supplied, and even fine cartridge oil filters (such as clean-up filters) will clean oil better than when it is new (yes, I have data). What we can't do is remove the chemicals related to combustion. For systems that require very clean fluid, it is common to use a dialysis-type off-board filter cart, to clean the fluid and put it back, because the fluid is fine, it just needs cleaning. In the case of an engine, the oil will itself cause a failure, due to the nature of the system. You can't compare engines and transmissions, they are completely different. I would compare a transmission more to a hydraulic system, where the fluid does lubricate, but also serves as an incompressible actuator and a heat conductor.

[ard]

We'll continue to disagree...

I am going to run UOAs on my ATF when it comes out, we can see what it looks like- maybe continue a rational discussion based on data and not marketing claims.

I *WILL* grant that new transmissions seem to rely less on fluid and clutches to modulate forces, hence there may be some rationale for longer intervals...

But hey, I think anyone reading this thread will find these kinda interesting...(and yes, I do know these refer to 'lifetime' fills).

A

[Quicksilver]

No arm wrestle here, however...........

I believe that most people who read this thread will conclude
that no matter what evidence or data is presented, the conclusion
will be that most people are going to do exactly what they want to
do regardless of any logical, coherent, evidentiary, conclusion.

Even if the engineer who developed the science of BMW transmission
fluid change visited this site and joined the discussion there would be
people who would know more than the engineer knows, argue him until
the cows came home resulting in the same conclusion. Regardless of
what you say Mr. engineer we know better so we are going to do just as we
please. So in the end what's the point......... Go therefore......

[ard]

Originally Posted by Quicksilver

No arm wrestle here, however...........

I believe that most people who read this thread will conclude
that no matter what evidence or data is presented, the conclusion
will be that most people are going to do exactly what they want to
do regardless of any logical, coherent, evidentiary, conclusion.

Even if the engineer who developed the science of BMW transmission
fluid change visited this site and joined the discussion there would be
people who would know more than the engineer knows, argue him until
the cows came home resulting in the same conclusion. Regardless of
what you say Mr. engineer we know better so we are going to do just as we
please. So in the end what's the point......... Go therefore......

Good point.

So all we can hope to do is bring the issue to people's attention- so they can consider whatever facts exist- and they can make their own decision.

Instead of only blithely following their CBS indicator on the dash (which won't unfortunately tell them to change ATF at any mileage)



A

PS If you know that engineer's email, PM it to me.... thx

(I kid)

[Quicksilver]

Originally Posted by ard

Good point.
So all we can hope to do is bring the issue to people's attention- so they can consider whatever facts exist- and they can make their own decision.
Instead of only blithely following their CBS indicator on the dash (which won't unfortunately tell them to change ATF at any mileage)



A

PS If you know that engineer's email, PM it to me.... thx

(I kid)

I wish I did, or I wish they would take part in the thread.
Seems like it would be helpful regarding a lot of issues
people have transmissions/fluid or otherwise.......

[BustedKnuckles]

So I just did a round of maintenance on my 07' X5 4.8L... Engine oil, coolant, brake pads, AND... transmission fluid and filter...

Car jacked up in the air on jack stands and perfectly level front to back, side to side...


Removed the splash shield

drained transmission fluid through plastic drain bolt

removed the old filter

followed the instructions on the new filter, put some fluid on the o-ring on the filler neck. carefully placed the new filter back onto the bottom of the trans and hand tightened the bolts.

Went in the proper sequence of tightening the bolts until everything was fully re-assembled.

using a fluid pump, I used ZF lifeguard fluid until it started to overflow from the fill hole.

tightened the fill bolt. put the wheels back on, dropped her back onto the ground and started her up. Runs fine.

THE PROBLEM - when I put the car in reverse to back it out of the garage, it sits for a second and puts itself back in park. Tried again, happened again...

Try a 3rd time and it stays in reverse.. hmm ok... start to back out of my garage and all of a sudden i hear a loud fast clicking noise. like really loud... like metal smacking together. and the car puts itself back in park. I shut it off.

At this point i"m getting on here to figure out what I F'd up... please give me good news...

UPDATE: Just tried to back it down the driveway again and got to the end of the driveway and reverse isnt working... It's still in reverse but gassing it just revs the engine... WTF... put it back in drive and it goes up the driveway fine but then acts like it slipping as I pull it in the garage.. How did I just destroy my transmission by changing the filter and fluid?

[genew]

Originally Posted by ard

Good point.

So all we can hope to do is bring the issue to people's attention- so they can consider whatever facts exist- and they can make their own decision.

Instead of only blithely following their CBS indicator on the dash (which won't unfortunately tell them to change ATF at any mileage)



A

PS If you know that engineer's email, PM it to me.... thx

(I kid)

This won't help you in any way but thought I'd throw a couple of facts in. I have driven over 105,000 miles in an e53 2001, and 110,000 miles in an e53 2004 and the original tranny fluid was in both and the transmissions were shifting perfectly. Have 35,000 on an e70 and the same.

[ICX5]

Interesting points on both sides of this issue.

I believe all parties agree that with a lack of actual technical data around the transmission operation, wear, fluid degradation, etc., then empirical data becomes a major source of information. But even here, when speaking specifically about BMW transmissions, we have a lack of actual data. Sure, there are folks with actual experience with transmission failure or friends who experienced it (so one, two, maybe five data points), but what of the million plus units that BMW and their suppliers have put out to date?

Is there consideration to any "motives" that BMW might have in recommending extended servicing of the transmission:

1. BMW wants your transmission to fail as soon as possible so you will buy a new car sooner?

2. BMW doesn't want the income (or more accurately the dealer's income) that would be generated by servicing the transmission every 5,000 miles, 10,000 miles, or whatever mileage number you'd like to insert

3. BMW believes their engineering staff in that the transmission doesn't need regular servicing of the fluid (again, the term regular seems up for debate). Perhaps the engineers are using a balance of technical and actual field data. Maybe the engineers were tired that day and just guessed?

I think this list could go on and on, but I find it hard to believe that BMW choose the recommended service interval for no particular reason (good or bad).

If 5 out of 10 BMWs were experiencing transmission failure at 50,000, 60,000 or even 100,000 miles, you would think the word would be more widespread.
I'll be the first to admit, I haven't been following BMW drivetrain reliability over the past years, but by the looks of some of the BMW owners on this forum and the number of posts (length of membership), there should be some word of transmission failure problems if it is occurring. Perhaps the majority of members are not keeping their cars much past 100,000 miles, but I think some history would still show up.