BMW 330i / Ci / Cic ZHP (E46 2003 - 2006) Automatic Transmission Reliability

[Lanister]

Hey guys, I wanted to resurrect this topic for a bit longer. It seems as though some sources indicate that a simple AT fluid change is enough and others state that, because of the torque converter retaining a substantial amount of old oil, it should be flushed again right after the initial change. While it makes sense, I'm surprised that videos by Bavauto and a number of DYI's don't even mention the flush. Thoughts?

[Hermes]

It needs to be flushed probably 7-8 times to get all the fluid out. I've done it 3 times so far

Edit: also, the car must be running and in gear when filling it so the level is correct. The car needs to be in the air. I did it at my buddies shop

Pic of the valve body when I changed the filter, gasket and all the bolts

[Vas]

That is going to be super expensive if you are using redline oil

[Hermes]

Yup, and I did use redline... I like my car

Eventually I'll S54 and 6MT it and prob move the M54 to the E21

Edit: The issue is you flush maybe 60% of it, so you do the flush then drive a min of 100 miles so it mixes evenly. You then flush again. You will keep diluting it but it takes a ton of oil to get it completely changed because you will never get 100% of it out.

[Lanister]

It needs to be flushed probably 7-8 times to get all the fluid out. I've done it 3 times so far

Edit: also, the car must be running and in gear when filling it so the level is correct. The car needs to be in the air. I did it at my buddies shop
Pic of the valve body when I changed the filter, gasket and all the bolts

7-8 times? What are the suggested flush intervals?

[Hermes]

You don't need to do it that much, I'm just saying if you're anal and want it 100% changed. I'll probably do it one more time (4 total) and say it's good enough. Interval for me is change, drive 500 miles, change, etc.


Going forward I will change it every 25,000 until I get around to a drivetrain swap

[ranger]

My first BMW - 2005 BMW 325i sedan auto - is still going strong with over 200,000 miles - I "sold" it to my son at about 160,000 miles when I got my ZHP (RIP). I never changed fluid, etc. I am very suspect about changing fluids in high mileage gear boxes - my theory is that we have no idea what will happen to seals, etc when you flush/change fluids, etc. I worked for a long time at a paper mill that had gear boxes still in service from the 1930s - we never changed fluid/flushed those gearboxes - just kept them topped off for that reason. I know, I am a heathen.

[Lanister]

I hear what you're saying, ranger. There's definitely something to be said about that. In my experience, the issue with seals had more to do with changing oil types. For example, going from conventional motor oil to synthetic is known to make seals leak on high mileage engines but as long as you stick with the same oil type, it should be safe.

With regard to tranny oil changes, my experience tells me that it does make a difference. I have an old 2001 Eurovan running VR6 motor and an old automatic transmission, which is known to be the weakest link of the entire vehicle. Although the manufacturer advertised it as "life-time" the transmission fails exclusively due to lack of oil changes. As such, I have been changing transmission oil every 30k and have been happily trouble free on that end well past 150k mark. What was always blatantly obvious after each change is that the transmission would shift MUCH better, smoother, and quicker. My ZHP is at 90k and I can already sense that some shifts are not the smoothest and even though I don't know how it's supposed to be (I just bought the thing) I have a strong feeling that there's are improvements to be attained through an oil change.

[Hermes]

This will also help. I put it in the 740 but not the ZHP yet. I will on my next/final change

[Dave1027]

I've been running that red Lubegard in my tranny for about 6 months now. Not sure if it helps.