XSeries-forum

To be clear - you're suggesting there is no need to change the oil in a gearbox ....?

no, not at all, although they are supposed to be good/sealed for life like any oil it degrades with heat cycles and time, just perhaps thought I would maybe mention that what looks like the major game stopper in the zf auto box seems to be the primary shaft bush which fails through use and not through old oil etc.
Im not an expert or anything but have spent a fair amount of time on other makers forums researching this ZF box I have and the popular consensus and denominator for the thump in the box and bad or no selection is the above.

along with Torque Converter, Oil Pump, hydraulic controls, bad oil - it needs doing every 60k, sprag clutches and all kinds of other faults.......

Glad I've got a manual

Dortmund was well worth the trip, zf were fantasic. The gearbox is all done, I can't say I notice to much difference but I am no expert driver.  They did tell me that the sealed for life element is a bmw quote and ZF themselves recommend a change between 80,000 and 100,000. So mine had a new filter new oil and seals etc, I would of gone without the car as Dortmund Xmas markets were brilliant and the Germans made us feel very welcome. All in I ate more meat then I can care to remember and drank some proper beer for a change,