[DeTomaso] Gear lube

[Mike Scardina]

I just finished changing my transaxle fluid.  The TSB's recommend GL4 lubes. I couldn't find any in my area (other than some really inexpensive lube whose name I didn't recognize), so I used Castrol EP 80W90 which is a GL5 oil.  I chose that one since one of the GL4 lubes recommended in the TSB was Castrol's product.  The GL5 seems to work fine, but I just read on the Castrol web site that GL5 fluids have extra additives that can be corrosive to yellow metals (brass and bronze) over time.  Other web sites also stated the same thing about GL5 lubes, except some say that the GL5's can be designed to be backwards compatible to be used where GL4's are specified. Castrol's site said to follow manufacturer's recommendations.  Does the ZF have any brass or bronze parts?  

I also just had a new ZF put into a Superformance GT40 and haven't asked the installer what he used for gear lube.  Is there any reason to think that the recommended lube for a new ZF would be any different?