E46 & E39
X3 and X5
E60 – 5series
E65 – 7series
E87 – 1series
E90 – 3series
According to the manufacturer the oil in these gearboxes are a lifetime oil. When I get these cars with early stages of gearbox faults; transmission light on – I usually recommend a change of oil and the filter(E46 & E39).
What I find is that the gearbox oil that I drain out is already burnt and very black.
To extend the life of your automatic transmission I would suggest you change the oil and Filter(E46 & E39) every 80000km on all vehicles.
A clogged filter can produce slippage and hesitation. See pic of filter
Gearbox Plastic Sump
With the E60, E65, E87 and E90 the oil sits in a plastic sump.
Like with all plastic parts they have a heat cycle and eventually it cracks and oil seeps out. Low oil can lead to premature failure too.
Sump usually starts to leak between 150000km – 180000km.
See pic of sump