The reservoir holds about a quart of fluid, but the rest of the system (steering box and hoses) hold nearly another quart. Or at least that is true on the 108.
You can suck the reservoir dry, top up, run the engine and repeat the process until all clear fluid is present. But that takes a lot of fluid. Some people just suck out the fluid from the reservoir and top up, at least that is a partial change.
You could drain the resevoir, top up and the crack open the bleeder valve on the side of the steering box, attach a line to the valve and place the end in an empty milk jug. Next step takes like five hands, hold the line in the jug, start the engine and keep the reservoir topped until clear fluid enters the jug. Secure the bleeder and close the system.
When you have the reservoir dry, that is a good time to replace the steering filter at the bottom of the reservoir.
'73 280SEL 4.5 (9/72)- RIP
Only 8,173 units built from 5/71 thru 11/72
'02 CLK320 Cabriolet - wifey's mid-life crisis
2012 VW Jetta Sportwagon TDI...at least its a diesel
Non illegitemae carborundum.