According to the lubrication thread toward the bottom of this list of message board topics, L/S additives are not required. However, you may buy the additive separately if you begin to have problems or (given the price of ZF parts and service) are rightfully paranoid.
Just my $0.02.
quote:
Originally posted by lee:
Lloyd:
My regular mechanic put non-posi fluid in my transaxle about 100 kilometers ago. Any problems