Don't worry bcredliner, I rarely mistake my father's motor home for an E53 -it's a little clumsy maneuvering on some of the boat ramps we use! The observation was just that modern ATF fluids have a very long life if not overheated or contaminated. You're right about that driveshaft. It was a $4200 deficit, even with a used transfer case.

2002 X5 3.0 244,042 miles (today)
2004 325i 109,000 miles

I always start with manufacturer's service recommendations, and then take it from there, modifying based on experience, judgement, and monitoring the results over the vehicle life to that point.

I would not dismiss changing the fluid every 50,000 as illogical. Illogical is a strong word. I do think we are mixing up two different issues here though.

1) If the fluid hasn't been changed in a long time (pick your interval....) then I believe it can be a risk to change it. Doesn't mean it will fail after a proper change, but there is a risk. I would avoid that risk if I could. The first and most obvious way to do that is if you are going to change it, then to change it more frequently. I think that if you are changing it every 50,000 miles you have far less risk than if it went double or triple that. In that sense, your specific fluid change regime is not illogical at all.

2) If the fluid is being changed because of an economic proposition that doing so will pay the owner back for the cost involved, whether by causing the transmission to last longer or perform better up until eventual failure, I think that is overly optimistic. There are too many failures due to non-fluid related causes, and when that happens then everything spent on fluid changes is thrown away. The lack of system reliability we have seen suggests that planning to run a transmission a very long time simply by changing the fluid is illogical.

Dinan tranny software saved my transmission! I was getting a check engine light periodically for the common P0741 code (torque converter lock up issue). Since the addition of Dinan software I haven't seen it once. Shifts stronger and faster too.

My post was that changing the fluid at 50,000mi. CANNOT be dismissed as illogical. I have changed the fluid every 50,000 miles and believe that is the best practice.

:iagree: with number 1

I don't know whether to agree or disagree with 2. What you mean as a very long time may be quite different than my view. I don't know why I would include failures not related to fluid in a payback calculation about worth of changing fluid---has nothing to do with fluid, has nothing to do with this discussion.

I do change the fluid for the purpose of better performance and reliability. I don't think anyone has enough facts to substantiate lack of logic or over optimism abut that. I know that I don't. That might be the case if the posts about transmission failures were more detailed and both sides of the debate were posting equally.

Lumping all the repairs for any transmission results in my current perspective--- somewhere after 75,000mi. I am likely to have a transmission problem. if I make it over 100,000mi. I am in the minority. It's the best guess I can make but it not anything to make a decision from because I am not comparing 4.6 transmissions with mine.

Hmm... how hard is it for a low-skill wrench-swinger to change the trans fluid?

Going to save for a rebuilt either way, jic. ;)

I think it has everything to do with the discussion. If these transmissions were wearing out from old age, then anything you gained by doing a series of regular fluid changes would potentially be the upside, weighed against the cost of those changes. That is based on there being a correlation between transmission failures and fluid condition.

But if there are a lot of transmission failures not related to transmission fluid (and there are reported to be), then we need to consider that information. Owners that have a failure (for non fluid related reasons) will have to tear into the transmission anyway. The opportunity for benefit is reduced. Essentially, it comes down to the newer fluid being potentially good, but irrelevant.

Funny...

I was just thumbing through my owner's manual. It clearly states..

Automatic Transmission Service: Change ATF every 100,000 miles.

So BMW does recommend servicing the automatic transmission.

It depends on the year of manufacture. They flipped back and forth, not necessarily on the same transmission models, but on the same base vehicles.

The service manual for my '03 ZF5HP24 states the same. When I pointed it out to the Service Manager at a FL BMW dealer he stated that the manuals were not updated and the "lifetime" trans sticker is what they go by. FWIW, I was told BMW defines "lifetime" as 100k miles! :confused: Seems to me they have a financial motivation to replace them vs service them. Not just for an $8k trans job but all the additional work a +100k X5 will no doubt require.

I don't agree that we know that changing the fluid is irrelevant.

I thought you meant none fluid related failures---failures where no fluid is present. As an example-software.

I agree that a payback should include the cost of the fluid/filter change. And, the cost of fluid change added to cost of transmission repair. Unfortunately, it doesn't matter what we include-- a payback calc is meaningless because we don't have enough information to make it accurate--I wish that weren't the case.

I don't consider a payback calc as an endorsement to change or not to change fluid. The bottom line of this payback would be cost per mile. Since there are no min/max mileage for transmission failures or average cost of repairs we are talking gobble-de-gook.

The primary question--is there a potential or real benefit to changing fluid or not. Obviously, since we are having this discussion we don't know if there is a real benefit. As to potential of a benefit, I think the answer is yes. As to the question, is it a waste of time and money, nobody knows.

What we do know is that we replace oil and other fluids because they degrade over time and they all have a maintenance schedule. (I find it hard to think of anything that doesn't degrade over time). We know that BMW recommends to change the fluid if it has been overheated. We know that BMW has both suggested to change the fluid at 100,000 mi. and have said the fluid is lifetime fluid (whatever that is---when is a X5 considered dead?) We also know that BMW has not said--whatever you do, don't change the fluid because it will cause the transmission to fail. Add to this that we hear about enough transmission problems that many of us are concerned about transmission reliability and longevity.

Personally, that means to me it is a good idea to do something that logically could extend the number of miles I drive before I have a transmission problem. And, if I do have a problem it could cost less to fix. And, something so I don't hesitate to stomp the go pedal and fire the nitrous.

As it relates to the fluid is so much better than it used to be--OK. That it gets better as it ages---not OK--not apples to apples, might as well have been a used mayonnaise study. Though if anyone wants the fluid from my next 50,000 mile change, I will sell it at 50% of the cost new, plus shipping.