My wife has a '95 S320 and she asked me to check all the fluids and such today (which I did like a good husband). The PS fluid looks to be up about half-way in the cylinder that sits on top of the PS pump, but there was no dipstick or any other indication that I could see to show how full this reservoir should be. Do I need to top it up or is this a normal level? My gut tells me it is low, but I am no whiz on power steering.

Do I really need the MB fluid or is there an aftermarket one that will work? I don't mind paying the MB premium so much as the long drive to the dealer!