I have a 1992 400E with 165K miles and it does have the serpentine belt.
I have read a lot of posts and debate on Power Steering Fluid type and am still confused. My Owner's Manual say MB Power Steering Fluid (nothing about ATF, Dexron II or anything).

What is MB Power Steering Fluid in terms of composition and what is in it?

Auto Parts store yesterday told me they thought Pentosin CHF 11S was right, which is a Mineral Oil based fluid at $30/Quart!! They could not find a definite equivalent reference so I do not have high confidence.

Is there a filter on this Power Steering system?

Thanks,
Kim

__________________
1992 400E (W124) - 177K Miles - fun car!!

I have often used Febi PS fluid which is supposed to be the same as the MB, but the MB fluid from the dealer should cost only $10-12/quart, versus $6-7 for the Febi, and you can blow your savings searching for the Febi (which I get at BAP). There is a filter in the bottom of the reservoir - remove the top nut, deep 10mm socket I believe, and pull stuff out until you find it.

I use regular power fluid from Autozone. Am I doing something wrong?

__________________
2008 S550
2010 GLK350
1997 E420 (retired)
2005 CLK500 (retired)

MB list of approoved fluids for recent vehicles. MY 92 500 had what looked like transmission fluid, I drained it and changed the filter, and gasket, the fluid I purchased here is clear (FABI) I think. The power steering fluid I flushed with was also clear (autozone). The later cars use the same steering (hydraulic) oil, as the suspension fluid
http://www.startekinfo.com/StarTek/outside/9511/?requestedDocId=9511