Originally Posted by Riggodeaux

Do you have any service history? For example, papers in the glove box, chalk marked on the diffs, transfer case, etc.? It certainly looks in fine shape for 140k miles. Plugs may have been done around 100k; the PO who kept it in that good a shape may well have done the proper service. If you can locate a cooperative BMW dealer, I'd try to get a print out of dealer service and work from there. I'd pull the fill plugs on the diffs and transfer case and give the fluids the eyeball/smell test, absent history, and change them if suspect at all. As for the auto tranny: search further for the pros and cons of doing a partial drain/filter change and fill; no standard/school solution there. Congrats on what looks like a nice purchase! Personally, I would do a short interval fill [5k miles?] on that oil had have it tested at Blackstone, then proceed forward with an oil that meets the BMW LL01 standard [some Castrols, Mobil1 euro 0w40, the Pennzoil Ultra high-detergent, etc]. The search tool here can be a little glitchy, but spend some time looking and you'll find the info on coolant repairs.