Do you have INPA/DIS? Scan your transmission and the codes will help you narrow it down.
- I do have INPA/DIS but haven't managed to connect it properly...yet
You can try to reset trans adaptations after the fluid change too.
- I'll do this for sure once I've figured out if the the refill/clearing codes have been successful.
Have you done transfer case oil change already? It's just 1 liter. A very expensive 1 liter though lol!
- Haha no I haven't but I will now that you mentioned it (my biggest issues is getting to the dealer from where I live...long drive :/ )
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.
- You are indeed right, the issue here for me is getting the whole rack without it costing me an arm and a leg...it's either the dealer or ebay, being in Norway the dealer is a big no no unless it's something only they have and anything over $20 from ebay is taxed (25%) extra...in addition to the ridiculous delivery prices (sometimes higher than the cost of the part itself).
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.
- My steering is "sticking", feels like something is catching but does not make any whining noise. I do get a squeaky noise when turning a quarter (sounds like really dry metal against metal..hence why I think the tie rods are the culprits and maybe ball joints). I replaced the fluid in the reservoir only a while ago, it seemed to work better but the issue quickly came back. However, I definitely need to replace the hoses as they are leaking for sure.
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
- Radiator and hoses were replaced back in 2013 due to a tiny crack in the radiator (no overheating caused or anything bad though). Waterpump replaced in 2010 (was making a scratchy noise), everything else is untouched since factory. I should really replace it all as a precaution but not while I am in Norway.
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.
- The thing is, I have no loss of fluids other than the usual consumption of engine oil (I top up with less than a liter every 5-6 months or so, same goes for the coolant). Even the power steering fluid is not down but I can see the hose is wet and there is an obvious leak from underneath (confirmed: fluid in the pics), nothing on the ground though.
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.
- I did read that post, thanks for reminding me! Let's hope all is order there though 
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.