Question

[300kplus]

Is replacing the automatic transmission filter and some of the other things listed as routine maintenance [transmission fluid] by this advertisement realistic? For instance on Transmissions I thought they were sealed? E39 M62...
Thanks

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[dannyzabolotny]

BMW used to claim that the transmissions were filled for life, so they never provided a dipstick or any easy way to service them. That was a lie though, and BMW later changed their tune on it, recommending regular transmission fluid changes every 60k. A lot of mechanics will still refuse to change the fluid in a BMW transmission past 100k miles, due to the widespread myth that changing the fluid will break the transmission.

The best way to service these transmissions is by doing a drain and fill, that'll gently replace some of the old fluid with new fluid, without the shock of a power flush. Drain the old fluid, drop the oil pan, install a new Filtran filter (don't bother with aftermarket garbage), reinstall the oil pan, fill with any fluid that meets the LT 71141 spec (I've used Febi, Pentosin, and ZF Lifeguard, all are good). The fill procedure is a little messy, you have to be under the car to do it. Fill it up until it starts dribbling out, then start the car and run through all of the gears. Add more fluid until it starts to dribble out again. Take it for a test drive, then wait for it to cool down completely. Start the car and open the fill plug when the transmission is between 30ºC – 40ºC, if there's a small dribble of fluid then it's filled to the right level.

My 540it's transmission shifted like utter garbage when I first bought the car, with 174k miles on it. The fluid was original, as was the filter. After a fluid and filter change it shifted incredibly well. Everyone that drives my car says the transmission feels really good, and I beat on it constantly— I even took it to the drag strip and did a bunch of burnouts and hard launches with no problems. I have 195k miles on the transmission now, and it still works very well.

[edjack]

Further, I would suggest a 3X drain and fill, to get most of the old stuff out. Replace the filter before the third fill.

I would agree with Danny about flushing.

[djb2]

It's unlikely that the transmission filter ever really needs to be changed with just a fluid change. The filter is large, and has relatively little to filter out unless a disaster occurs.

The risk with changing the filter is that some aftermarket filters for ZF transmissions used a filter media with high pressure drop, and had ill-fitting o-rings where it attached. This resulted in the oil pump sucking air, which causes noise and various problems.

I don't see the value in multiple successive drains and fills, unless you are leaving the car in the air. Even then it quickly becomes a waste of fluid, as you are mostly draining new fluid as it takes the rapid-circulation path while old fluid remains in the unused actuating cylinders and torque converter. You are better off switching to a shorter change interval (30K miles).

[edjack]

How do you get the torque converter changed?

[djb2]

How do you get the torque converter changed?

I don't think that there is any way to do that, short of replacing it. Even with the TC off of the car, it's difficult to drain the fluid from it. I had mine out of the car for two weeks while working on the transmission, and every few hours there was more fluid that could be sucked out of the hub.

The torque converter's lock-up feature is one of the fluid paths that is unlikely to activated while on a lift or jack stands. That, along with all of the other chambers and cavities, is why a "complete fluid exchange" or "flush" is more marketing that reality. You should think of it as "refreshing the additive package" rather than "100% fresh fluid". Once you start thinking that way, a 100K-150K mile initial service and 30K mile subsequent service intervals makes sense.