In my opinion fluid properties such as dynamic/kinematic viscosity, pour point, flash point, foaming/aeration, copper corrosion, FZG gear scuffing resistance, etc. may be replicated by pattern/inventory-reduction fluids. However what is much more uncertain is whether or not the fluid matches the required friction characteristics.
These friction characteristics are critical. For example, the early ‘black-tag’ ZF 5HP30 transmissions fitted to the 540i, 740i/L & 840i (i.e. the 010, 011, 029 & 030 models) used only Shell LA-2634 fluid. The later ‘green tag’ versions of this same transmission (models 017, 026, 031, 032 & 040 – plus the Rolls-Royce, Bentley & Aston Martin models) - use only Mobil ATF LT71141 (like the 5HP24).
The difference between the two transmissions is the way the lock-up clutch in the torque converter is controlled. The friction characteristics of the two fluids are sufficiently different that getting the two fluids mixed up can, according to ZF, cause the transmission to fail.
The 5HP24 was designed without a torsional vibration damper in the torque converter to save weight and reduce length. It relies on a ‘continuous slip’ mode at lower engine speeds (around 3% slip between the impeller & turbine) to isolate the driveline vibration and, to achieve that, it needs a particular static-to-dynamic friction characteristic for the fluid.
If you use any other fluid than Mobil ATF LT71141 (aka ZF Lifeguard Fluid 5 or Pentosin ATF-1) in your 5HP24 there is no way of knowing if it contains the right friction modifier pack to achieve correct operation of the TC LUC. The torque converter costs a lot more than the difference in the fluid cost.
Phil
ZF video :
Oil Change Intervals for the ZF 5HP Series of Transmissions - YouTube