On the Power Steering
Replace both hoses (they provided their full life by now). Replace the reservoir with a ZF branded one. You will need three new clamps as well (two at the reservoir and one down by the pump) Flush out all the old fluid and add in new. Fluid color tells you what you need. Green or red stuff! Red= ATF+4 for example. I personally use Valvoline Syn ATF+4 from Auto Zone. When your new reservoir gets a few years on it, you can just replace the seal on the lid.

Like what has been posted before, this reservoir has a "weep hole" in the spin on lid and vents the mist on the side. A quick wipe every time your under the hood solves the issue. Your vehicle looks like it operated under a closed hood policy, "What happen there is not important". Kinda like a coffin...once in closed forever. Typical lack of maintenance and interest by a previous owner. Normal.

On the cooling system

I would disagree with others if you plan on long term ownership. Do it all now once and you will have peace of mind that all is well. Rad, upper and lower hoses, water pump, Thermostat, expansion tank, check the other heater hoses while you are in there too. Belts, w/p pulley (cracks) idler, and tensioners. All go bye bye.

Tip: Check the block under the pump/thermostat for pitting BEFORE reinstalling the pump. clean all areas with sand paper. Flush block when open. Lots of examples on this pitting issue posted. All from poor maintenance and improper coolants being used. Use BMW anti freeze only is recommended.

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2005 X5 4.8IS
The Blue ones are always FASTER....

Current Garage:
2005 X5 4.8is
2002 M5 TiSilver
2003 525iT
1998 528i
Former Garage Stable Highlights
2004 325XiT Sport
1973 De Tomaso Pantera, L Model
1970 Dodge Challenger T/A 4 sp Alpine White
1970 Dodge Challenger T/A 4 sp GoManGo Green
1971 Dart Sport, “Dart Light” package
1969 Road Runner 383
1968 Ply Barracuda 340S FB Sea-foam Green