Current work around X1.
The old 5.4tkm engine oil was fully 2 days drained and fresh Mobil1 engine oil was added.
I have driven + - 6-10tkm every year since 2017 and changed gearbox oil every year, this year the oil flowed out in a nice yellow color.
I replaced the seals on one of the Mechatronic where it contacts the gearbox.
Of course a new filter and ZF oil, now I can not change the gearbox oil for a couple of seasons.
New update soon.