X5 steering moan when cold

[Meestahbig]

2003 X5 3.0 150k proud miles...

Following my annual inspection, car started to moan when cold when I turn the wheel left or right, stationary or driving slowly. Fluid (ATF) might be low, I have not checked yet, but I read that the symptom of the noise when cold, is related to air in the system... and the article suggestion to change an o-ring. Does anyone know how this might apply to my X5? I will check to see if there is a leak, but other than the large o-ring in the reservoir cap, are there other O-rings? Maybe a hose connection is loose?

Also - what are people recommending for ATF fluid?

Hopefully the pump is still okay, bc I saw it is expensive, but seems like junkyard has it cheap, if I am changing it myself it might pay to go that route despite not knowing how long it will "last"... I did that with an AC compressor and so far so good (many years later now).

Thank you.