The car is a 1993 300SD, which is the 3.5 liter 603.971
What brought the fluid issue was that fact that twice,
at 902+ degree ambient temperature, I had a problem
steering at low speed or when the vehicle was stopped.
The steering wheel had some vibration coming through
it and a sound like something rubbing, etc. ( the
sound is hard to explain).
Most of the postings and advice have suggested
checking the PS fluid, which is between the min
and max in the resovoir. However, the resovior
is only about 1/3 full.
1993 300SD (286k + miles)