Approved fork fluids

I expect that these approved fluids are not even available these days.  The BMW magazines of the day were full of all kinds of suggestions for fluids that worked, most were nonsense.  To start with, so much fiddling with the forks often resulted in fork misalignment and the mechanic had no clue.  The results of a change in fluids weren’t controlled, so often errors factored in to make the results useless.