[fe7565]

There are multitudes of comments and videos on this contradiction... Comments below to help me (and others in the same situation) to navigate in order to make a decision.

Most dealers will advise against touching high mileage transmissions with no history of fluid changes. This seems to be related mostly to liability issues in case a dirty/worn transmission dies after a flush or fluid change. Hard to explain to the customer what may have happened. So they just refuse to do it, or charge unrealistic prices to deter you or to cover their ass.

Until about 100K miles in my car, I was on the fence about taking BMW's "lifetime" transmission fluid statement seriously vs the ZF transmission maker's 62K miles guide. Since then I have been reading up on it, and this is what I gathered one is facing with a 113K miles (183k km) car...which is already 83K km's over the ZF's service limit.

Do not flush, unless you replaced your transmission fluid every 30k miles or so, or you usually drive on mostly highways at moderate speeds. A dirty transmission would not benefit from a flush as the dislodged sludge and solids may clog the delicate oil passages/solenoids. So, you should know your car's history.

What about changing it when already over 100K miles? The best (insurance) would be to take a sample of the transmission oil, and send it in for analysis. If it comes back fairly healthy then changing should not be an issue at all. In a normal transmission oil change (vs flush) you are replacing at a 70/30 ratio (70 percent new/30 percent old remains).

I plan to replace my fluid this month. But will not do an oil sample analysis, because I believe that my transmission is fairly spared from abuse. The risk of letting it go forever without a fluid change is much larger vs doing it now (in my opinion).

I bought my transmission fluid service kit from FCO Euro a year ago. The fluid change is actually not that complicated, there are some traps and cautions to obey. The largest risk I am facing is to get the car securely high enough to be able to get under safely and comfortably enough to do the job. As I am getting older, I am realizing more and more that a few tons of metal toppling on me is quite detrimental to my health.

Attached my notes I gathered from various sources and the official ZF procedure files.

[pbonsalb]

The typical drain and fill is probably more like a 50% change than a 70% change. Do it a second time and the percentage increases slightly but the returns are diminishing. Better than nothing.

There are ways to fully flush but I have not seen them detailed for these cars yet. Basically you intercept a transmission cooler line to make a drain and keep filling from a fill port or the other side of the intercepted line until fluid that is new looking starts draining out. I am about to do this on a family member’s Nissan Frontier. On my M5, I did the drain and fill and plan to do it a second time soon.

[OUGrad05]

Can you even find dealers to do this work? I tried to get my ZF8 cars done at BMW dealers and they wouldn't do it, granted this was years ago when the ZF was still fairly new. I had indy shops do it.

[Silence*]

I've began to think of it as the lifetime of the car while its still under warranty with the first owner, which after 3 or 4 years they most likely should have traded it in and gotten a new one... hence "lifetime".

I did change the lifetime rated fluid in my old 2004 325ci with the GM automatic, despite people saying not to a few years ago because it had 260,000km on it. This was the first time it was ever changed out and the original fluid was still in pretty decent shape surprisingly. It immediately shifted smoother and gave me no other issues in the 16k I put on it before selling it. My 435i is at 136k right now and based on ZF's recommendation I'm planning for a fluid change this spring/summer.

[ZL9M2]

Just make sure to be familiar with the process. It's not a simple drain and fill. Need to run the car and heat the fluid to gauge proper fill level.

[fe7565]

Originally Posted by ZL9M2

Just make sure to be familiar with the process. It's not a simple drain and fill. Need to run the car and heat the fluid to gauge proper fill level.

Yes, attached step-by-step ZF guide and notes by others in first post.

[fe7565]

Originally Posted by pbonsalb

The typical drain and fill is probably more like a 50% change than a 70% change. Do it a second time and the percentage increases slightly but the returns are diminishing. Better than nothing.

There are ways to fully flush but I have not seen them detailed for these cars yet. Basically you intercept a transmission cooler line to make a drain and keep filling from a fill port or the other side of the intercepted line until fluid that is new looking starts draining out. I am about to do this on a family member’s Nissan Frontier. On my M5, I did the drain and fill and plan to do it a second time soon.

Depending on how much one waits for it to drain it seems people are taking out 3.5 liters to 5.5 liters (with most around 4.5 liters) from the 7.1 liters total. Some do it a couple of times to reach a higher ratio of new oil, but like you said, not sure if worth the money and the time.

[fe7565]

Originally Posted by OUGrad05

Can you even find dealers to do this work? I tried to get my ZF8 cars done at BMW dealers and they wouldn't do it, granted this was years ago when the ZF was still fairly new. I had indy shops do it.

Most dealers will advise against touching high mileage transmissions with no history of fluid changes. This seems to be related mostly to liability issues in case a dirty/worn transmission dies after a flush or fluid change and then hard to explain to the customer what may have happened. So they just refuse to do it, or charge unrealistic prices to deter you or to cover their ass.

[fe7565]

Originally Posted by Silence*

I've began to think of it as the lifetime of the car while its still under warranty with the first owner, which after 3 or 4 years they most likely should have traded it in and gotten a new one... hence "lifetime".
.

I also think this is the reason BMW calls it "lifetime". Quite irresponsible and a let down. Must have some legal reasons.

[LogicalApex]

I know this isn't about the Transfer Box, but on the G30 BMW defines the "lifetime" of the transfer box oil as 150K/km or 92K/m. Their lifetime is defined for how long they intended the part to live. It isn't that it should never be changed at all. Many just see whatever "lifetime" BMW has prescribed as too long from an oil changeover perspective.

I follow BMW recommendations FWIW

[OUGrad05]

Originally Posted by fe7565

Most dealers will advise against touching high mileage transmissions with no history of fluid changes. This seems to be related mostly to liability issues in case a dirty/worn transmission dies after a flush or fluid change and then hard to explain to the customer what may have happened. So they just refuse to do it, or charge unrealistic prices to deter you or to cover their ass.

Sure but they wouldn’t do it on my cars at 30k miles.

[fe7565]

Originally Posted by OUGrad05

Sure but they wouldn’t do it on my cars at 30k miles.

Probably, because BMW says "lifetime" and they (the dealers) do not have a mandate (from BMW) to do it even if under warranty. If you pay for it yourself as the owner and ask them to do it anyway, then they open themselves up for liability if something goes wrong with the job or with the transmission later on.

[fe7565]

Interesting.... What do you think about this comment? IMHO, not a bad idea, but will "waste" 4-5 liters of new fluid to get about 1-2 liters of mixed new/old fluid out. Small payoff for a big cost?


"What i did. Drain transmission. repalce drain plug. Fill transmission with fresh fluid. Run through the gears. Drain transmission a second time and replace the filter. Then fill, go through all gears, and top off. I wanted to flush the system with fresh fluid and then remove that fluid as it would become contaminated with the old in the torque converter. You wont be able to completely get out all the dirty transmission fluid, however, this cycles out some of the bad or old fluid in a attempt to replace as much of it with fresh fluid as possible."

[fe7565]

More info:

If you have a transmission oil cooler, you need to overfill with 0.5 L and run engine until transmission is at 75C (167 F). Which is where the instrument panel start showing the trans temperature. See Page 3 of the attached ZF procedure for details.

Also, for checking the trans temperature with ISTA+ follow post #10 from Bummerfest thread (see below). Seems to be the same used by FCO Euro in their video.
ISTA+: to read Trans Oil temp from Control Tree's ECUs screen go to EGS module ECU, call up ECU functions, then Diagnostic Scan, and select any reading you need.

https://www.bimmerfest.com/threads/h...-temp.1078649/

[Chihuahua]

Originally Posted by fe7565

"What i did. Drain transmission. repalce drain plug. Fill transmission with fresh fluid. Run through the gears. Drain transmission a second time and replace the filter. Then fill, go through all gears, and top off. I wanted to flush the system with fresh fluid and then remove that fluid as it would become contaminated with the old in the torque converter. You wont be able to completely get out all the dirty transmission fluid, however, this cycles out some of the bad or old fluid in a attempt to replace as much of it with fresh fluid as possible."

Exactly what I did with my E60 530i when I replaced solenoids/bridge seal/etc. Losing a couple of liters of fluid was worth the result. My $.02.

[pbonsalb]

Doing it twice slightly improves the ratio of freshly oil to old oil. I have done it once and plan to do it again. The returns are diminishing so I would not bother with a 3rd time.

[fe7565]

If you are doing the transmission fluid, may as well do the front differential (xDrive) and rear differential. The car has to be level, and the transmission skid plate is already off. Just use a different pump or clean it really well.

[ctcarbonari]

Great thread topic & excellent resource links in OP. That ZF video where they use the baguette to demonstrate the effects of particulate matter is one of my all time favorites. The pdf of the "how to" notes is a great resource as well. I especially enjoyed the "Here's what you need to know, that no one else will tell you section" Thanks.

Here's my 2-cents:

I had my ZF8HP serviced @ ~60k miles (Pan/Filter + Fluid). I tapped out on DIY at the thought of doing this on (4) Jackstands. The old man in me made that decision. I was surprised at how many Indy shops around town were either reluctant to do this procedure or tried to talk me out of it by saying it was "way too early".

I had a fluid only dump & fill performed again @ ~80k miles. (20k mile use cycle)

Prior to the results of my Oil Analysis (OA) I would have been 100% on board with doing the ZF service "twice" to achieve ~70-80% change over to new fluid. I still think it's a good idea and good practice; however, I don't believe it's as necessary as I would have intuitively believed. I've attached the OA results for those that care to geek out on the numbers. Notice the insoluables percentage difference between the first and second OA. I was fully expecting a higher value in 80k mile report (20k after the initial service).

I'd recommend sticking with LifeGuard8 Oil & ZF Pan/(Hengst? Filter). LG9 can be used & mixed with LG8 for the 8HP (I contacted ZF back when LG8 was hard to get.) It is a different color tho.

For those out there w/ (RWD) that use the M18x1.0 Drain Plug and want to replace the Plug only (i.e. when doing just a "dump & fill" w/ no pan replacement), well....good luck sourcing a quality BMW OEM from any of the usual suspects. Good news tho, they are readily available thru Mopar (Chrysler) and is where I got mine.

Fundamentally, I'm a believer in keeping fluids/filters changed regularly. They're the lifeblood of every mechanical system. FWIW, here's my PM/Service plan for my ZF 8HP tranny.
Pan/Filter changed every 60k miles + mechtronic sleeve (I may have the solenoid seals done @ 120k, still debating on that one)
Oil "dump & fill" every 20k mile intervals (mostly because it makes me feel better)

And.....the best for last.....Here's my interpritation of the definition of "lifetime fluid". It makes about as much sense as BMW's.

Build a man a fire, you'll keep him warm all night.
Set a man on fire, you'll keep him warm for the rest of his life!

[Chihuahua]

Just to add to this thread, thectsc.com is a great resource for ZF service parts. I've used them several times with multiple cars and they've been great every time. No affiliation, just a happy customer.

[fe7565]

Originally Posted by ctcarbonari

Great thread topic & excellent resource links in OP. That ZF video where they use the baguette to demonstrate the effects of particulate matter is one of my all time favorites. The pdf of the "how to" notes is a great resource as well. I especially enjoyed the "Here's what you need to know, that no one else will tell you section" Thanks.

Here's my 2-cents:

I had my ZF8HP serviced @ ~60k miles (Pan/Filter + Fluid). I tapped out on DIY at the thought of doing this on (4) Jackstands. The old man in me made that decision. I was surprised at how many Indy shops around town were either reluctant to do this procedure or tried to talk me out of it by saying it was "way too early".

I had a fluid only dump & fill performed again @ ~80k miles. (20k mile use cycle)

Prior to the results of my Oil Analysis (OA) I would have been 100% on board with doing the ZF service "twice" to achieve ~70-80% change over to new fluid. I still think it's a good idea and good practice; however, I don't believe it's as necessary as I would have intuitively believed. I've attached the OA results for those that care to geek out on the numbers. Notice the insoluables percentage difference between the first and second OA. I was fully expecting a higher value in 80k mile report (20k after the initial service).

I'd recommend sticking with LifeGuard8 Oil & ZF Pan/(Hengst? Filter). LG9 can be used & mixed with LG8 for the 8HP (I contacted ZF back when LG8 was hard to get.) It is a different color tho.

For those out there w/ (RWD) that use the M18x1.0 Drain Plug and want to replace the Plug only (i.e. when doing just a "dump & fill" w/ no pan replacement), well....good luck sourcing a quality BMW OEM from any of the usual suspects. Good news tho, they are readily available thru Mopar (Chrysler) and is where I got mine.

Fundamentally, I'm a believer in keeping fluids/filters changed regularly. They're the lifeblood of every mechanical system. FWIW, here's my PM/Service plan for my ZF 8HP tranny.
Pan/Filter changed every 60k miles + mechtronic sleeve (I may have the solenoid seals done @ 120k, still debating on that one)
Oil "dump & fill" every 20k mile intervals (mostly because it makes me feel better)

And.....the best for last.....Here's my interpritation of the definition of "lifetime fluid". It makes about as much sense as BMW's.

Build a man a fire, you'll keep him warm all night.
Set a man on fire, you'll keep him warm for the rest of his life!

Thank you for posting your experience, service plan, and the oil analysis tests. The analysis tests certainly give a peace of mind going forward. I am still on the fence, if I should do one in a few days when I will replace the fluid/pan at the first time at 113K miles. I am not planning to keep the car forever, but it certainly make a god second car. I wish I would have read up and educated myself on the "BMW lifetime" paradox years ago when I had a lot lower miles, because I would have replaced the fluid/pan a log time ago.

One note that seems to be missed by many, and also brings up a question to anyone who can clarify it, is this step of the ZF decision-chart where they mention cars with a trans cooling circuit where the thermostat opens at 75C. This circuit contains another 0.5 liters of fluid. So ZF says to over fill with 0.5 liters while replacing the fluid. Is that circuit (hoses) empty after draining? That's why the overfill by half liter? Because it that half liter of old fluid is still inside that circuit (hoses) locked behind a thermostat that only opens above 75C, then we have just overfilled the entire system by a half liter.

[BroDoze]

Dang ^^

[co_440i]

So it seems like the jury's still out on if we need to do this or not?