Is there a big price difference ? I would stick with the ZF fluid if not - but it is quite probable that there are other fluids that are OK - ZF doesn't make fluid - stuff comes from shell or somewhere like that ...with ZF specified additive package - which can't be that hard to reverse engineer by someone like Pentosin - but there is no incentive for either ZF or Landrover to spec alternative fluid - they want to sell their own stuff at good margins ....