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:/
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.
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? www.bobistheoilguy.com/ forums/ ubbthreads.php/ topics/ 4364043/ 1