I believe there are two different items that are affected by a reset, or whatever it is called.

The fluid condition monitor is supposed to know that there is new fluid in there, so it will know when the fluid is out of spec.

The transfer case just splits the power front and rear. However, you have x-drive, with a variable torque split. The x drive clutch packs have an actuator that applies pressure to shift torque front/rear. There was a reset procedure I read based on the actuator measuring its travel, so it knew where the engagement point was for the clutches. This is the one I would worry more about, as clutches not fully engaged could wear quickly.

It doesn't turn a light on because the driver is not supposed to change the fluid. The service manual describes the procedure.

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2007 X3 3.0si, 6 MT, Premium, White

Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue