Well, my DIY Rx would be to add a measure (probably start off with 1 to 2 Qts.) of kerosene to the crankcase, and let run a bit - at least to operating temperature while monitoring what you hear and see from the engine. Drain, repeat adding Mobil 1 0-40 weight to the kerosene with every cycle. -Until you clean it up from within.
Have you looked at the color of the trans. fluid in it's an automatic?
Have you looked at the coolant for signs of oil mixing in with it?
As far as turning over a nice used MB diesel to a relative, being that it's your Daughter, I would recommend you take the time to shepherd the car's maintenance along - even though the car is in a distant place. That is what I am planning on doing with m y old MB diesel at some point. I am fretting about the car's well-being in a relative's hands, but it will be all their's anyway at that time, but I know how you feel.
