Dick,
A couple of years ago I had work done on my ZF by Lloyd. When I picked it up I quizzed him to some extent on the proper gear oil to be used.
While some have posted here that Lloyd has specifically recommended one oil, my take away from our talk was that any quality gear oil, changed annually, will provide the lubrication protection that our transaxles require.
Not so critical in regards to the type, but that regular changing is what Lloyd was recommending.
I realize you are asking about additives but as this topic continually comes up I like to share the simple solution offered by Lloyd.
Larry
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