4kq ps fluid - Pentosin or ATF?

[Luis Marques <marques@rtis.ray.com>]

Well, I have decided it's time to replace the power steering fluid and
filter on my car - an '87 4kcsq.  Hopefully that will take care of some
of the squealing my car is making at idle.  Common knowledge is that all
early Ur-Quattros, Coupe GTs, and 4k quattros use ATF on the power
steering system.  My car, however, has this little sticker on the ps
reservoir warning that only "hydraulic mineral oil" should be used part
number  002 000.  Can somebody confirm if I have been "blessed" with a
Pentosin car, or if it's OK to use regular ATF?  TIA

Luis Marques
'87 4kcsq