Sorry to hear of your troubles. I have listed several links to info about the ZF transmission. I believe there is a disclaimer on the proper fliod in the fluid charts and some others. I'll have to check my database to get the actual document specifically cautioning against using anything but the ESSO fluid, but I know the lube chart linked here states essentially the same thing.
http://www01apps.zf.com/kst464/ZF_InteroeleV2_manager/Work/2010-04-01/TE-ML%2011_en0700.pdf
http://www.zftranspart.com/index.php?p=product&id=54&parent=28
http://www.zf.com/na/content/en/import/zf_na/startseite/sso/passenger_car_light_truck/car_driveline/lubrication_and_oil_requirements/Lubrication_and_Oil_Requirements.html
Cheers!