Lifetime auto trans fluid

[the dink]

When I first bought my 05 z4 and put it on the hoist I was surprised to see lifetime fluid sticker on the transmission pan. This I could not believe so I started some research. I called the bmw dealer and asked for a filter and pan gasket for my 5hp19 transmission, the parts guy said not necessary its lifetime fluid so no need to change. Come to find out my model car has two transmissions available, ZF 5hp19 or GM 5l40E. I did research on ZF industries who makes my model transmission and they recommend service every 50000 miles or 8 years. Besides that why would the transmission have a drain plug, which most don't have. Anyway I changed the fluid, filter and pan gasket. Got all the factory parts from ZF and glad I did. With only 30000 miles on car it was due. If you want to extend the life of your automatic change the fluid, if you don't the life of trans could be 50000 or 70000 miles who knows but it will have longer life if serviced.

[gas-can]

Simple caveat on this though: if you haven't changed your Trans fluid in a long time, it may be dangerous to change it. As a trans ages, stuff starts accumulating in the fluid (metal bits from the clutch packs,etc.). After a while, the transmission starts depending on the gritty fluid to actually work, so if you suddenly replace it, the trans may stop working/start slipping.

It's one of those things that you may be rolling the dice on.

Just my two cents.
-gc

[David70]

Originally Posted by gas-can

Simple caveat on this though: if you haven't changed your Trans fluid in a long time, it may be dangerous to change it. As a trans ages, stuff starts accumulating in the fluid (metal bits from the clutch packs,etc.). After a while, the transmission starts depending on the gritty fluid to actually work, so if you suddenly replace it, the trans may stop working/start slipping.

It's one of those things that you may be rolling the dice on.

Just my two cents.
-gc

Happened to read this recently -
http://www.cartalk.com/content/today...smission-fluid

They disagree and I don't know if they or you are correct. I don't see how gritty fluid could help it work properly.

[StickMon]

My ///M also has a lifetime fluid sticker on the side, but the inspection checklist says yours should be changed every 100k miles, and mine at each Inspection 2.

[RobMCoupe]

Life time fluid by BMW standard is the original warranty period of 4 years and/or 50k miles.

[StickMon]

I guess "life time" by BMW standards is the original warranty period.
I think that explains a great many things.

[Finnegan]

Originally Posted by StickMon

I guess "life time" by BMW standards is the original warranty period.
I think that explains a great many things.

Exactly. Another description would be "life" of component, which if you don't change the fluids is going to be a much shorter "lifetime".

[gas-can]

Nice article David.

I would definitely go with those guys but the logic against it still makes sense to me, and though not statistically significant by any means, I have seen enough cases first hand to stop me from doing it if the ATF already looks burnt by the time of replacement.


Not to mention I'm surprised they recommended the flush machine. The tranny guys I hung out with used to love that thing cause they thought it was one of the reasons why they got so many rebuild jobs. Their idea was that the machine can cause crud to dislodge and go block the many tiny orfices in the AT. Not to mention several manufacturers also seem to recommend against the machine, and recommend just dropping the pan and replacing the fluid while leaving the 30% or so in the torque converter alone.

This seems to be one of those questions that you get a different answer from everyone you ask

Either ways, it's just one more reason for me to get a manual

-gc

[bosstones]

Weird timing....I've been catching up on some old magazines I didn't get to read and there was an article in Roundel about this in Tech Talk. Mike Miller posted up a letter from ZF regarding their clarification about "lifetime fluids" in their transmissions. Unfortunately, it looks like I recycled that issue this Tues on trash day. If I remember correctly, they said 8 years or 100k miles.

[gtMc]

Originally Posted by gas-can

Simple caveat on this though: if you haven't changed your Trans fluid in a long time, it may be dangerous to change it. As a trans ages, stuff starts accumulating in the fluid (metal bits from the clutch packs,etc.). After a while, the transmission starts depending on the gritty fluid to actually work, so if you suddenly replace it, the trans may stop working/start slipping.

It's one of those things that you may be rolling the dice on.

Just my two cents.
-gc

I have this dilemma right now with my '03 automatic 540m sport. 113k on the clock, and have been debating the tranny fluid change for 20k miles now.

Gas-can's thought above is not as crazy as one might think. I too have heard something similar, and it might have been from Mike in Roundel, or my indy, cant recall. Goes something like this: Over time, enough microscopic metal particles come off the parts in the tranny and become part of your fluid, and the fluid actually expands a little. In addition, the contact points of the parts have now been reduced in size, and overall the gaps increase. As a result, the bulkier tranny fluid acts as a 'filler' and makes up for the larger variances in the tranny parts themselves. A fresh fluid would now result in tranny parts that are 'loose', and lead to bigger problems.

my sense is that these gaps are again microscopic changes but myself not being a mechanical engineer, I am overstepping by speculating further. It sorta makes sense though.

My indy has said that some never change the fluid and get 200k out of those trannies, other change it at 100k and have to replace it 10k later. He too said its a 'Roll of the dice'.

I keep meaning to email mike at Roundel to get his thoughts on my exact tranny. not the same as the Z, but similar concept.

[RobMCoupe]

My indy rebuilt my C230 tranny a little over 90k. He used to work for MB dealer. His job was rebuilding tranny because it goes out around 100k. His recommendation is to change the fluid every 60k. I have no problem after changing fluid.

I just picked up a 94 325is automatic beater. It has 168k with no maintenance history. I am going to change all fluids. We'll see if this theory holds true or not.

[David70]

Originally Posted by gtMc

I have this dilemma right now with my '03 automatic 540m sport. 113k on the clock, and have been debating the tranny fluid change for 20k miles now.

Gas-can's thought above is not as crazy as one might think. I too have heard something similar, and it might have been from Mike in Roundel, or my indy, cant recall. Goes something like this: Over time, enough microscopic metal particles come off the parts in the tranny and become part of your fluid, and the fluid actually expands a little. In addition, the contact points of the parts have now been reduced in size, and overall the gaps increase. As a result, the bulkier tranny fluid acts as a 'filler' and makes up for the larger variances in the tranny parts themselves. A fresh fluid would now result in tranny parts that are 'loose', and lead to bigger problems.

my sense is that these gaps are again microscopic changes but myself not being a mechanical engineer, I am overstepping by speculating further. It sorta makes sense though.

My indy has said that some never change the fluid and get 200k out of those trannies, other change it at 100k and have to replace it 10k later. He too said its a 'Roll of the dice'.

I keep meaning to email mike at Roundel to get his thoughts on my exact tranny. not the same as the Z, but similar concept.

I don't agree with "the fluid actually expands a little". The fluid won't expand, you either have clean fluid at level x or dirty/burnt fluid at level x. If you shaved off 10% of everything in the transmission the level of fluid would still be the same.

I could see the viscosity changing as the material in the transmission was worn off but if thicker fluid was the answer to keeping the old transmission running correctly then I would think there would a market for this fluid. New, thinner fluid caused it to fail, add thicker or the old fluid that you removed and it should be ok again?

I think the article I included makes a lot more sense, customer that has never changed the fluid is starting to have transmission problems so decides to change the fluid for the 1st time. Problems continue or get worse, he thinks the fluid change was the cause. Or customer waits until 175k miles to change the fluid for the 1st time, trans. goes out at 200k, he blames the fluid change as everything was ok until the change.

Problem with all of this is the fluid is changed at some point, person has failure, notes when it was changed and either blames it on the change or doesn't, it all seems to be speculation without any facts.

[gas-can]

I'm also weary of the fluid expansion claim.

The logic for my thinking is this: the AT uses clutch packs which are continuously submerged in ATF. These packs are how the transmission engages the different planetary gears. As a transmission ages, these clutch packs wear out and deposit their material into the ATF (not unlike how a clutch in a MT wears, except there is no fluid submersion there). This aging is exacerbated if the ATF itself is damaged (ex: if overheated due to towing/uneven change intervals/age, etc) as it can no longer keep the AT within temp specs.

So after a while, the ATF will be grippier as it has all the little friction material from the clutch packs. This thicker fluid will assist the clutch packs do their jobs. If a person suddenly changes the fluid, you still have the same clutch packs but as they are worn and now don't have the more grippy fluid to aid the changes, you get a slipping transmission.

There's also the thing with leaky seals being affected by the lower viscosity fluid, but that's another thing.

My feeling is that if you have routinely replaced the ATF, then it's good to keep changing it regularly. If however you have lapsed and allowed the ATF to get damaged and let the AT run on the burnt fluid for a while, it's probably better to just leave it as is because the damage probably has already been done and you are on borrowed time anyway.

This also goes with what the Carguys talked about- once the tranny does start acting weird, people change the ATF in the hopes it will (quickly and cheaply) fix it. The damage is already done by then, however, and the change in ATF exacerbates the problem, leading people to unfairly blame the ATF when it only made the underlying problem more apparent.

Add the above with the flush machines and you got a pretty nice setup for even more damage!

gc

[David70]

I guess as long as you get a car without a lot of miles on it and change it regularly you have the best situation, after that there is a lot of speculation as to whether or not you are better off replacing the fluid or just driving it until it fails or you sell the car before it happens.

Unfortunate as just never replacing fluid is backwards from how I like to maintain things.

My dual clutch DSG Audi A3 requires trans. fluid change every 40k miles which I get done right as scheduled, at the dealership, as I have doubts about others doing it correctly or with wrong fluid. I am at 150k miles, I wonder how many other DSG owners are getting it done when it costs about $300.

[gtMc]

David, GC, all very good points. interesting thought on Grippier ATF, and the difference in viscosity, and to your points, they would just make a fluid that is more appropriate for elder tranny's if this were true.

Incredibly when I've tried to have mine changed (I'd prefer to invest and prevent damage), I have actually been discouraged. Maybe BMW would rather get me to buy a new tranny one day, then to let me change my fluid.

[the dink]

Lots of interesting input, but I would not care how burnt or how long ago transmission fluid was changed in any vehicle I owned. I would change the fluid no matter what, If your trans takes a dump after a service it was on the way out anyway. Most trans shops charge extra for hard part damage in transmission so why not get the gritty burnt stuff out and let good parts remain reusable instead of trashing the rest of unit.

[gtMc]

I just wrote to Mike Miller at roundel on a few topics and included this one on ATF. First time reaching out to him. I bet he'll say to change the fluid, and will post it when I do get an answer from him.

[David70]

Good idea about Mike Miller's opinion. From his "Lifetime Maintenance Schedule" (see part in bold). -



Automatic Transmission Fluid (ATF) and Filter: Variable every 15,000 to 60,000
miles

For older automatics using synthetic ATF, drain interval 30,000 miles. Old fashioned petroleum ATF, drain interval 15,000 miles
The short answer for the modern BMWs with “lifetime fill” ATF: Change it and the filter at least every 60,000 miles using ONLY the factory BMW proprietary ATF or current equivalent.

Long answer: At various production dates in the mid-1990s, which vary according to model, BMW switched to their so-called “lifetime fill” ATF in automatic transmissions, as well as manual gearbox lubricant and differential oil. The reason for this, as far as anyone can tell, is marketing and not engineering – the idea being to foster the notion of the low-maintenance BMW.

There was no explanation of what “lifetime” meant, i.e., lifetime of the car, the component, or for that matter the driver. If it was the component, then obviously anything could be “lifetime fill”. The factory’s initial position was that these lubricants never need to be changed. Then, some time later, it came out that “lifetime” means 100,000 miles. Many dealerships are now recommending manual gearbox and differential oil changes be done at customer expense every 60,000 miles. Every independent BMW technician I know recommends a 30,000-60,000-mile interval, and many recommend Red Line synthetic oils, but not for automatics with “lifetime fill” – you need the factory proprietary ATF for “lifetime fill” automatics. Older automatic transmission models, which do not have “lifetime fill” should have ATF and filter services every 15,000 miles if using petroleum ATF; every 30,000 miles with synthetic. However, the modern automatic transmissions are different. No one knows exactly what BMW’s proprietary ATF is, so no one knows if there are viable alternatives. We do know that BMW dealerships charge about $500 for an ATF and filter service, due to the price of the ATF. And that’s assuming you can get them to do the job, which is not often the case.

Bavarian Autosport (www.bavauto.com), Pelican Parts (www.pelicanparts.com), and perhaps others are now importing the proprietary “lifetime fill” ATF at reasonable prices, which they sell along with filter kits, for independent BMW shops and do-it-yourselfers.
It is risky to drain a previously un-maintained automatic transmission with high mileage, even though if it were my car I would probably chance it. Still, I have seen it happen too many times, where a well-meaning owner or technician performs an ATF and filter service on a neglected but well-shifting automatic, and then all of the sudden it starts slipping. I can’t explain it, but my feeling is the fresh ATF flushes a bit of sludge from a place where it was doing no harm to a place where it does do harm. Overfilling, underfilling, and cleanliness are also issues in ATF and filter servicing, but these should not be problematic for a professional BMW technician, dealer or independent.

BMW has backed off its lifetime fill mantra for automatic transmissions, currently recommending an ATF and filter change every 100,000 miles for the current BMW models at this writing. My inclination is to tell people to change “lifetime” ATF and filter every 60,000 miles.
However I have seen BMW automatic transmissions that were maintained break anyway. In that event, say it happens at 90,000 miles, you would like to have the money you spent on the ATF and filter change to put toward your new automatic transmission. And if I told you to spend it on maintenance you’re probably not going to be very happy with me.
On the other hand, I have seen maintained automatics last 200,000 miles. I have also seen un-maintained automatics last 200,000 miles, although both are very rare. There's just no predicting with these transmissions. When you choose to buy an automatic transmission, you also buy into the vagaries of the darn things, which is one reason technicians hate them. Whether to maintain a modern BMW automatic is up to you. At automatic transmission replacement time, we are confronted with the reality that the local transmission shop cannot rebuild BMW automatic transmissions, even those built by GM (BMW’s GM transmissions bear no resemblance to GM transmission in domestic cars). There are some domestic specialists who concentrate in BMW automatic transmission rebuilding, and you’ll see their ads in Roundel and Bimmer. However, I have no current experience with domestic rebuilders. My experience in the past is…well, the owner wound up buying a BMW factory rebuilt automatic transmission every time, and this is the course I recommend to readers – “back to the dealer.”