Do you have INPA/DIS? Scan your transmission and the codes will help you narrow it down.

You can try to reset trans adaptations after the fluid change too.

Have you done transfer case oil change already? It's just 1 liter. A very expensive 1 liter though lol!

Tie rod I would get the assembly with the rack end and ball joint so I wouldnt have to touch that area for a long time. Lemforder is OE for that part.

For the power steering, why do you need to replace the reservoir? Filter is not replaceable but the reservoir can be removed and it can be cleaned. Reservoir is not that expensive though so it's up to you. Hoses, yeah, those like to leak over time and I need to replace mine too.

Coolant flush and re-fill would be a good time to inspect and replace other system parts like hoses, etc. Depends on what you have done to the system since you got it, it can go all the way to a full overhaul. I would check all the pulleys, tensioners, water pump, visco fan, fan blade, and drive belts while there

The fluid in the pics could be spread all over those areas by driving at speed. Cant tell what kind from the pics. Could be engine oil or PS fluid.

Removing the airbags, I would check for excess negative camber and replace parts to get it back to spec if needed...usually the upper control arms. OE Lemforders or since you may be lowered, maybe look into the adjustable control arms a member posted up about recently.

Fluids - BMW OE coolant, pretty much any LL01 engine oil, and ZF Lifeguard 6 for the tranny. PS is Dex III but I think some BMW's use Pentosin for the PS? The PS filler cap will be marked for which. BMW OE X-drive transfer case fluid for the transfer case.

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04 X5 3.0i auto
03 X5 4.6is