I reviewed the detailed WIS Service Sheets (AP00.20-U-12081B/8.11.04 and AP00.20-U-1206BC/14.7.05) for my 2003 E500 and didn't see any service requirement for draining/replacement of the power steering fluid. There's service requirements listed for changing the brake fluid, the coolant and the transmission fluid........seems to me that power steering fluid can become "aged" just like these other fluids and should eventually be changed, maybe at the 100k mileage point. Anyone have any service data on this?

I haven't seen any requirement either

The local dealerships around here try to convince you that you need to do it every 25 minutes. Actually every couple of years which seems ridiculous to me but I will monitor the color to see if it needs to be changed. they claimed that Mercedes used to change it when Mercedes was offering free maintenance.

Okay, thanks for the input. I changed the PS fluid on my 04 Volvo S60 recently since I had to replace the PS Pump anyway and it was pretty dirty even with only 54k miles. I'll bet some auto manufacturers specify changing PW fluid at some mileage point and our MB vehicles' design and technology for that issue shouldn't be any different.