Those ZF 5HP19 on that 530i on that are robust transmissions that will last few hundred thousand miles.
Don't let them drive with a P0741 code - Slipping torque converter. What happens is the torque converter will not lock up and the slippage will cause a over heating of the transmission fluid. This will in turn cook the transmission.
The fix is not a fluid change, but to change out the torque converter with an updated unit. Best to get a new torque converter from the dealer, most rebuilts are hit and miss. Although some people reported to have good luck with
Eriksson Rebuilts or
517Trans rebuilts.
Changing the torque converter is cheaper then getting a whole new trans.
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