ZF Lifeguard 6 - FF - ZF 6HP19 - 120k miles

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13
Location
Ontario
I changed the factory fill (FF) trans fluid on my 2006 BMW 330i with the ZF6HP19 trans last August. I didnt like the idea of 12 year old fluid and filter, even though its lifetime there is plenty of evidence of these transmissions developing issues without proper maintenance. That being said, as long as usage and temperatures remain moderate the thinking is that the fluid and filter should be 'lifetime'. In the summer I did multiple 6 hour plus trips on the highway and drove the car hard whenever I get the chance. It's been really hot out and I figured I was putting the trans through some pretty harsh conditions. I want to keep this car in good shape for as long as possible, so I thought changing the fluid and filter would be the best move in terms of longevity. Also there were a few shifts that I didn't love (5-6 upshift at highway speed, 2-1 downshift on braking, 1-2 upshift under light acceleration). Immediately after the change, starting it up and driving it around felt fine but no immediate difference. However, that changed when I reset the transmission adaptives (clutch prefill and stroke learned setpoints). The trans then shifted way smoother than before and the bump from 5-6 at highway speeds was gone. I got a used oil analysis done on the fluid, and here are the results. On the right is a VOA sample from here (https://www.bobistheoilguy.com/forums/ubbthreads.php/topics/4364043/1) [Linked Image from i.imgur.com] [Linked Image from i.imgur.com] The fluid came out deep brown/black with what I assume is wear from the last 12 years and 120k miles. However, I did notice some shavings and black debris. The smaller particles are about 1/16" in size with a couple that are 1/8" and the big one being 1/4". I think this is fine, I don't see any obviously destroyed parts. I was told by a coworker in the transmission department in my old job that: " I would say this amount of clutch/trans debris is pretty normal (maybe even lower than expected) for 100K+ miles. The dark material is likely clutch material, but this is normal. Clutches adapt to the clutch paper wear over time, so it is unlikely to result in trans slippage. I would take a magnet and run it over the material to see how much metal you have. The metal you do have is likely just fine aluminum shavings and that is normal. The biggest thing is keeping debris out of the transmission main control. The filter is usually really really good at that - Transmission filters are really fine and will catch all of that debris." See the below link for pictures of the fluid (orange pail) and the pan with disassembled filter. Disassembling the filter was really interesting - I got to see more shavings that the filter trapped. They appear to be aluminum since the pan magnets didn't pick it up, but the magnets do have a lot of little shavings that look like fuzz. I think the aluminum comes from the torque converter, but I am not sure where/how all that alum gets worn off the TC. https://imgur.com/a/InYYOuZ [Linked Image from i.imgur.com] It seems as if the fluid was pretty well used. I planned to use a cheaper alternative for the next change ($25/liter is insane). However, I ended up replacing a few more liters with ZF LG when I experienced transmission slippage 10 months and 10k miles after this job. After much research on the topic, stressing, and replacing a few seals, the problem was finally solved by replacing the shift solenoids. So since 120k miles ~9L of new fluid has gone in to the trans in the last 10k miles. It can't be a full 9L drain ad fill since I did 6L at 120k and then 3L at 130k. How 'fresh' is this fluid? What would be the next change interval?
 
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5,205
Location
Atlanta,GA
Thanks for sharing ! Pity that BS universal averages are based on 44k miles rather than something longer. BTW there may be a specific re-learn procedure for your version of the ZF6HP. This is outside the adaptations re-set. Re-learn procedure.
 
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Nate_L

Thread starter
Messages
13
Location
Ontario
I am aware of this. I believe it is important to re-do, but not entirely necessary. I think the way the transmission is programmed is to use look-up tables for clutch preload pressure and application pressure. Those values are learned through monitoring gearshifts. That is why there is both a dynamic/static shifting component to the learn (starting from stop and going to highest gear, and holding a gear and cycling speed). This adaptive drive procedure is designed to fill out those tables immediately so the customer doesnt experience any bad shifts. If the memory is cleared then the tables will get filled out eventually. After doing the fluid change last year, I reset the adaptations and then did the relearn procedure. After the solenoids this year again I did the relearn procedure. Both times it has worked.
 
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1,313
Location
Athens, GA
I love how manufacturers aren't putting change schedules in their manuals, but the actual manufacturer of the trans recommends 60k mile changes. "ZF Aftermarket recommends a transmission oil change for ZF transmissions every 100,000 kilometers or after eight years at the latest. Important! Service intervals can vary with other transmission manufacturers. For example, for the Mercedes G5 or the Volkswagen DCT (DQ250), maintenance is scheduled after 60,000 kilometers. At very high operating temperatures, oil ages faster than under normal conditions. Depending on driving style and individual driving profiles (e.g., a lot of high-speed driving, trailer operation or sporty driving), shorter change intervals are advisable." Todays throwaway society at its best. You did good though, most people would just drive it to destruction.
 

Nate_L

Thread starter
Messages
13
Location
Ontario
I'm a little disappointed the previous owner didn't change the oil sooner, but realistically i'm not sure this would have helped much. I still had solenoid failure at 130k. $350 in parts, a day's work, and the car was back on the road. It took me about a month to commit to it, but it did solve the issue. Now I plan to drive to destruction. Not sure if ZF should recommend a solenoid change too, at 120k miles. A bit much for preventative maintenance but would have saved me a lot of headache. In my case i'm not sure doing fluid at 'proper' intervals would have made much difference. Perhaps it would have given added peace of mind.
 
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35,281
Location
NY
Originally Posted by MolaKule
Doing fluid changes at approximately 30k minimizes varnish buildup on solenoid valves, a major cause of sticking and failure.
Good advice. I can only imagine how many people buy into the filled for life mentality and wreck their transmissions as a result.
 

Nate_L

Thread starter
Messages
13
Location
Ontario
I have a couple of questions about that. Which types of fluids are more prone to the varnish build-up? Dexron, Mercon, Shell M1375? And what would be the mileage that they start to degrade? What exactly is varnish, and How does the varnish impact the solenoids? Does it affect the seals on the solenoids? As far as i'm aware the ZF6spd transmissions are known for their failure at high miles, I don't think it's due to varnish in every situation.
 
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1,313
Location
Athens, GA
One of the things that varnish will do is eat up any clearance in the interface and cause things to bind up. Probably not a good idea for precision machined parts that need to move freely.
 
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5,205
Location
Atlanta,GA
Originally Posted by demarpaint
Originally Posted by MolaKule
Doing fluid changes at approximately 30k minimizes varnish buildup on solenoid valves, a major cause of sticking and failure.
Good advice. I can only imagine how many people buy into the filled for life mentality and wreck their transmissions as a result.
Originally Posted by Nate_L
I'm a little disappointed the previous owner didn't change the oil sooner, but realistically i'm not sure this would have helped much. I still had solenoid failure at 130k. $350 in parts, a day's work, and the car was back on the road. It took me about a month to commit to it, but it did solve the issue. Now I plan to drive to destruction. Not sure if ZF should recommend a solenoid change too, at 120k miles. A bit much for preventative maintenance but would have saved me a lot of headache. In my case i'm not sure doing fluid at 'proper' intervals would have made much difference. Perhaps it would have given added peace of mind.
Think of it like this, more frequent fluid changes on the transmission then it would've been reflected in a higher sales price for the car.
 

Nate_L

Thread starter
Messages
13
Location
Ontario
Originally Posted by ctechbob
One of the things that varnish will do is eat up any clearance in the interface and cause things to bind up. Probably not a good idea for precision machined parts that need to move freely.
That should show up in the UOA right? What are the consituents of 'varnish' and do they read high in the UOA? If it's not measured in the blackstone UOA what company offers varnish detection?
 

Nate_L

Thread starter
Messages
13
Location
Ontario
Originally Posted by MolaKule
Doing fluid changes at approximately 30k minimizes varnish buildup on solenoid valves, a major cause of sticking and failure.
Want to bump to ask this question again. I'm genuinely curious, what are the consituents of 'varnish' and do they read high in the UOA? From what I understand varnishing is when you have solid compounds forming in the fluid, like a resin. I read some of Molakule's old threads. Would that show up in the UOA? If it's not measured in the blackstone UOA what company offers varnish detection?
 

MolaKule

Staff member
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21,599
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Iowegia - USA
Varnish is mostly the result of oxidized polymers forming on surfaces and will not show up in UOA's. Some transmission flushes claim to remove this varnish. Another theory is that the LXE esters in LubeGard Red will remove these varnishes over time.
 
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1,464
Location
California
"Lifetime fluid" speaks more to the lifetime of the vehicle than the lifetime of the fluid... it's up to you. So if you plan to keep the vehicle long-term, you must realize that there are no lifetime fluids.
 
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7
Location
Bay Area
Varnish is mostly the result of oxidized polymers forming on surfaces and will not show up in UOA's. Some transmission flushes claim to remove this varnish. Another theory is that the LXE esters in LubeGard Red will remove these varnishes over time.

I've seen Cummins or some diesel maker offered a special motor oil for engine cleaning to solve a specific problem they were having with deposits. It was a full non-crude based synthetic, probably with a lot of cleaning agents, too. I agree precision solenoids would not like varnish. I bet a decent amount of solenoid problems are from varnish; the rest from coil/electrical/mech issues. I'm transitioning in Redline ATF through drain and fills to see what happens. The Redline D6 is supposedly all Group 4 & 5 based on an email question answered by Redline. Right now it's 2 gallons of Redline D6 and the rest is Mercon SP. I pumped out all the old LG6 fluid at 100k miles from the cooler return 1L at a time until a couple liters ran clean. Just getting the old LG6 fluid out and 100% Mercon SP made a nice difference. I was having hard 1/2 and 2/3 shifts, which went away. Swapping in the 2 gallons of D6 made cold shifts better, I think, but not a huge improvement. I tend to believe the chemistry of G4/5 oils dissolve varnishes over time.
 
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7
Location
Bay Area
Based on a limited number of data points, I am thinking the chemistry of G4 and G5 oils dissolve deposits, but have no science or training. I saw Cummins offered an advanced oil to clean up a model of their engines that was all G4/G5 and probably a ton of additives.

Do you know if G4/5 oils would indeed clean up or dissolve deposits?
 

4WD

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15,144
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Texas
"Lifetime fluid" speaks more to the lifetime of the vehicle than the lifetime of the fluid... it's up to you. So if you plan to keep the vehicle long-term, you must realize that there are no lifetime fluids.
Yes … and ZF Lifeguard is analogous to the dude who sorted Corn Pop … and not a lifetime fluid 🌽
 
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