Replace lifetime oil with atf?

[s50b30]

I have 2 zf transmissions, one 320z and a 310z.
The 310z should use dextron of some sort.
And the 320z is supposed to only have a lifetime oil.

Is it important that I use lifetime oil on the 320z?
Are there any diffrences in the transmissions, or just a gimmick by bmw? (I have no idea)

[pbonsalb]

Try Redline D4ATF in the ZF trans. Works well.

[MarcoZandrini]

The different designations are made by the manufacturer, Zahnen Frabrik, aka ZF. There are real differences between the trannies.