Lube

This was the subject of some debate at 'Vegas this year. While everyone agreed that 75W90 gear-lube was the stuff you need, the debate was whether you need Posi-lube additive due to the multiple limited-slip clutches in our ZFs. Lloyd Butfoy will NOT endorse any particular brand of gearlube, but finally did admit that Posi-lube helps some cars.... if you use non-posi gear lube and your machine then creaks and pops going around tight corners at low speeds, add some posi-lube supplement to the gearbox (Ford also has a brand). Or, you can play it safe and simply use a gearlub for posi-type differentials. Any major brand of gear-lube will work just fine. Be sure to add enough to fill the cases, though.

Thanks for the info Jack. I understand the debate about limited slip or not, as some say yes, some no. Also some recomenend GL4 or GL5 (whatever that is).

The red owners manual states SAE 80 AP GL5, so maybe that is what to look for (but nothing about limited slip - unless GL5 means limited slip.

I recently asked ZF in Germany this very question. The reply was .. SAE 80W/85W.
The man at ZF who knows the 5DS25 transaxle is Karlheinz Bieg. Email address is karlheinz.bieg@zf.com.

Today I picked up some Sta-Lube Limited Slip Hypoid SAE 80W90 API GL5 from Pep Boys. From all the advise, looks like this will do it. Thanks.