Does it like to be run hard? Mine would mostly sit idle, shuttling kids around, with occasional road trips.

I had a VW TDI and it REALLY wanted you to ride it hard otherwise the intake manifold would get crudded up with carbon. I'm curious if the gas or diesel turbo's are similar where they don't like to sit or just plod along.

Are you doing the maintenance yourself? Is there a service guide floating around? When I had my k75 there were really good tech manuals (from BMW) and forums with DIY tips/tricks/videos - spline lube, general wrenching, etc.