Attention for all 2006 BMW X5 4.4, power steering fluid reservoir indicates ATF fluid. But it is not ATF, it is called Lubrizol Additive Fluid from BMW only. My steering has a small noise present when I turn steering wheel at low speed. BMW San Francisco corrects this issue with BMW technical Bulletin which suggests that they need to use Lubrizol. Thank BMW, my car is under warranty. It will be costly to correct Steering wheel noise. You can use ATF at own risk.

Keep that in mind.

Thanks