[DeTomaso] ZF oil choice?

[Panteratime]

 Folks,
Hope all finds you well.  It's been quite awhile but its time to change  the ZF oil again.  Although car has only about 1k miles since last change--its been a quite a few years.  :(
Last time I changed it I used Mobile 1--- 75W-90 Synthetic gear oil.  Are there any new recommendations?  Is the process still to drain old and slowly fill till it weeps out of side plug?   
Thanks!!   
Cliff Z-New York