Just picked up the the car from the mechanic after steering pump replacement (hoses are leaking, presumably). After a day or two the steering is "notchy" again. I checked the fluid level and it was OK, but then I noticed the color of power steering fluid was dark red-brown. Almost black. As compared to the clear fluid I just bought. Does it mean somebody filled up the power steering reservoir with the ATF fluid? How do I fix it?

 

Someone indeed did put atf in there. You need to drain all that out and put the correct Eurospec power steering fluid in. Stuff I bought was green I think, but I don't think power steering fluid is strictly color coded.

https://www.fcpeuro.com/products/hyd...-liter#fitment
Another fluid I used on the same car.

 

Yes, I bought the good stuff. How do I drain it? I read somewhere to disconnect the return line from the reservoir and start turning the steering wheel while refilling the reservoir with the correct stuff. The question is do I do it with motor running or the motor off?

 

Yes to do a flush you'd have the motor running to use the power steering pump to push the old fluid out while you put new fluid in the reservoir.

here's a handy link that explains the procedure

https://gobdp.com/blog/perform-power-steering-flush/