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]

Originally Posted by JWoody

HHhhhmmm, this is a good point. My MKIV VW GLI is a daily driver with a 6SPD manual tranny, but I do 40K tranny oil changes with AMSOil. I believe in what BMW says for their vehicles, but I am considering doing 50K Tranny changes for our X5. But I plan to use BMW's oil vs AMSOil. Just my .02...

-J

Manual trannies are a whole different kettle o fish...IMHO

A conventional manual has no hydraulic circuits, no clutches in the fluid path, relatively low heat...fluid will last quite some time. In my M5 and 996TT I've done tranny and differential changes and the fluid is surprisingly good even at a 50k change interval. (I even wasted my money on a Used Oil Analysis on the tranny fluid at 50k in the bmw..fine, but stabilizers getting 'thin')

A

PS I wholeheartedly believe in OE fluids for changes, especially in warranty. I don't really buy into any of the 'lubricant hype' that red/roy/ams/etc is a 'better' race oil/whatever... give me frest factory fluid at decent intervals (unless it really is a race car )

[JCL]

Originally Posted by Price

That's the thing: it used to be this way (mileage would be substracted from the service interval @ double rate for period when engine temp < certain degree), but I believe in all recent bimmers it's straight consumption, and nothing more. For US E46 it's 667 gallons, iirc.

Originally Posted by ard

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

This is a description of the oil quality sensor that BMW started using in 2005 or 2006 on the N52. Current parts books show the same part number, so I suspect it hasn't changed. Oil additive depletion is calculated via capacitance changes in the oil. It isn't a complete measure of oil quality, but simply one more factor for the DME to add into the distance to change calculation.

[JCL]

Originally Posted by ard

Did not see a 'cooler maintenance' in their schedule...nor do I think such a thing exists. Clean the fins??? that kind of "maintenance"?

Since heat is the enemy, maintaining the transmission cooling system is key. The thermostat could be replaced, the cooler and lines could be inspected. I wouldn't expect to see it in the BMW schedule, but you already have the schedule; you asked what type of maintenance would have the biggest impact in extending transmission life.

Originally Posted by ard

If you can show me ANY data that supports a "100,000 mile, unlimited years" lifetime on ANY ATF, you get a beer.

How about transmissions over 200,000 miles with the original fluid? Real world data? There are posts on this forum. Here are a couple that I came across quickly.

Originally Posted by a regular poster

2001, 118000 miles (189000 km). Still going strong. Not much problems and failures.... The original oil is still in the tranny...

Originally Posted by another regular poster

I have 115,000 miles and I have the original oil in the tranny as well. I have never heard of a transmission on a BMW X5 going out because of bad oil. .

If those tranmissions can go those distances on the original fluid, doesn't that suggest that the factory fill fluid can last just fine?

Originally Posted by ard

This is an interesting argument- although I'd need to know where the drain is- and if the valve body is drained, the TC, or what

I assumed draining the fluid through the pan, the valve body being drained when the filter is changed, and the torque converter not being touched.

Originally Posted by ard

How long (will the fluid last)? BMW says 'no time limit' or 100k.

Life of the transmission, whatever interval fate and non-fluid related failures cause that to be.

Originally Posted by ard

I am truly surprised at both the argument that a fluid change is a risk (afterall, BMW does recommend one, so how can it be a risk?), and the argument that ATF has virtually no life limit....

The entire point was that doing a transmission fluid change incurs a risk. If there was no risk, it would make complete sense to do it regularly, given that we agree that clean fluid is in general a good thing. It can be a risk whether or not BMW recommends doing it. Compare it to surgery; you can often repair a problem with surgery, but surgery is generally not without risks. It is a tradeoff of likely benefits versus potential downside. I also do think that ATF has a life limit, just that it is longer than the MTBF (mean time between failures) of BMW automatic transmissions. All this would change if we had posts about regular transmission failures involving burnt fluid or clutches, at mileages that correlated to having missed fluid changes.

Cheers

Jeff

[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.......