Xoutpost.com - View Single Post - Has anyone done a Transmission filter and fluid change and caused more issues?

JCL · #**169** 03-25-2015, 03:41 PM

Well, I thought the thread was dead twice now, but it keeps going. I think it is fair to keep it going (just don't read it if you don't want to) but let's keep personal attacks out of it.

I think the reason it became a pissing match is confusion over the evidence provided, and frustration. This is long, but hopefully will summarize the positions previously stated.

As posted way back in post #17, there are different recommendations for different BMW transmissions (even within the E53 family). For the ZF and GM transmissions in X5 models up to 2003 (5 speeds) BMW published that it is a lifetime fluid (owner's manual, clip shown above). They put a similar sticker on the transmission. I owned a 2003 model. And in the US Service and Warranty booklet, they include a line that says change it at 100,000 miles. I don't recall that in my Canadian service booklet, but I don't have it any more so can't confirm. So there is conflicting information, always has been, and any claim that it is only one or the other seems a little silly to me. For the 2004 models onward (6 speeds) I don't believe BMW used the phase lifetime transmission fluid any more on the E53. That is the basis of the discussion about different models that use different fluids having different recommendations. I don't know what the sticker on the transmission says for those years, but the owner's manual no longer said lifetime. We also know that if the recommendations change, BMW publishes service bulletins and links them to the technical manuals. Those manuals show changes in recommended service intervals for non-related components during the years in question, but not for the transmission fluid. I think we can fairly conclude the recommendation didn't change. Take a look in the service manuals to confirm.

As to whether any member has experienced this, the answer is yes. I said so near the beginning of the thread. It wasn't my own personal vehicle, and it wasn't an X5. It was a customer's vehicle in an independent shop I worked in. But it was still personal experience. I saw the transmission and laid hands on it. The assertion that that means that the wrong fluid was used, or that the job was therefore done incorrectly, is what sparked much of the debate. That is an accusation of incompetence. The failure analysis we performed found particles in the valve body. There was a lot of buildup in the transmission. There are more examples, but I am thinking of one specific one here. A ZF transmission at 100,000 miles may or may not have that degree of buildup. Certainly, that specific transmission I described above used an older spec fluid, which wouldn't have helped. And it was pre-electronic controls, so there was no protection in the transmission.

Many accept the above failure mode as being possible. That is why some who decide to change their fluid, for valid reasons, do it earlier than recommended. They are reducing the risk of their being any buildup significant enough to elevate the risk of subsequent problems. Also, the fluid is newer so it is still keeping the transmission cleaner.

There is a lot of fear expressed on boards of transmissions blowing up if the fluid is touched. I don't think there should be fear. There should be rational discussion. On one side, there is a risk. On the other side, there is a benefit of fresher fluid. That is a risk/reward calculation. As to the risks, I personally think they exist. I don't think they are so high that fluid should never be changed. But shops with experience doing transmission work have seen sufficient examples, in some cases, that they don't want to touch it. They buy the theory, and they want to avoid the risk. Fair enough. That is how this particular thread started. And if the shop is trusted, and can actually lay hands on the component, then their opinion trumps keyboard diagnosis, IMO. Others think the risk is non existent, and so they are happy to change the fluid without a further thought. Fair enough. It is perfectly OK to have our own opinions, and do our own risk analysis.

The number of failures in the above scenario is not a big percentage. It is enough to be noticed, but when people change their fluid and say they got lucky, I think they weren't, they were in the norm. Most don't fail. They shouldn't be surprised it is fine afterwards, most will be.

Now to the benefits. If people are changing due to concerns about oils wearing out (wrt lubrication properties) then I suggest that isn't a compelling reason. Lubrication is low on the list of what matters to a transmission fluid. What does matter is that the fluid viscosity is within the range that the transmission can adapt to. That the fluid level is correct. That the fluid doesn't foam. That it doesn't have water in it. That it isn't burnt. That the friction modifier additives are still there in sufficient quantity to enable the precise engagement characteristics that ZF designed for when they designed the transmission (and eliminated a torsional damper, relying on clutch slip to damper torsional vibrations, from memory).

Whatever the risk/reward calculation, it shifts left or right depending on the operating characteristics at the time. If the transmission has failed mechanically, it is obviously a losing bet to throw new fluid at it to see if the fluid fixes a leaking seal, a broken retaining clip, or whatever. But if the transmission is experiencing shifting problems that could be explained by a fluid being out of spec, then I think it is reasonable to change the fluid and see if it helps. If the fluid is the only problem, then new fluid will resolve the issue.

If we go back to a transmission that isn't experiencing problems shifting, and the risk/reward calculation, then it should come down to an economic life cycle analysis. Does changing the fluid extend the useful life of the transmission? I agree that the fluid wears, and that eventually, it will lead to transmission failure. That isn't in dispute, I don't think. The discussion centres on whether that will occur before or after the transmission would have failed from other (non fluid related) causes. Those with maintenance planning backgrounds (look at the posts by srmmmm) run economic analysis calculations that compare the cost of three or four changes to the life extension. His transmission is proof of how long transmission fluid can last in an E53, not a guarantee, but a challenge to those who simply say the fluid is worn out at 100,000 or whatever. He appears to have come out ahead. And n=1. Also, most of the discussion has been about ZF, and I think he may have a GM transmission in a 3.0, IIRC.

The entire discussion about what BMW recommends for intervals, in this thread, was initiated to support a contention that there can't be any significant risk, that it is a myth, because if there was then BMW wouldn't specific that change interval, even in error (because they contradicted themselves in two owner's books). Significant hasn't been defined. I don't think BMW have weighed in on whether there is a contamination or mechanical risk to a high mileage fluid change; they appear to be silent on the issue. They don't appear to be worried about fluid wearing out, as they instruct technicians to reuse fluid. I think they are basing their recommendations on life cycle cost analysis that shows a lack of evidence that changing the fluid will extend the transmission life. For all the service procedures that BMW has created, analyzed, tested, documented, done risk analysis on, etc, the respective procedure is listed in the service manual. And there isn't one for changing transmission fluid. So they presumably saw no need to develop one, for whatever reason. Infer what you will, but they certainly haven't said it is safe or there is no potential impact. They are silent on the issue. In my own opinion, the risk reward calculation may be close enough to balanced that they don't have a single opinion.

For my part, I start with the manufacturer's recommendations for service. If I did not have any severe service/duty operation I would go with 100,000 if I bought a new vehicle today (unless it had a different interval recommended). If I towed a large trailer (we are considering it now) I would think about testing the fluid several times to establish a trend, or just change it early. If I had a higher mileage vehicle that had never been touched, I would leave it alone. But that is all just me.

I think it is an interesting topic, and regret that it sometimes descends into personal attacks.

Jeff

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