Why does a diesel burn oil?

I have a 1988 190 Diesel that has 700000 miles on it and it is burning oil. How can I stop it?Why does a diesel burn oil?
The rings have alot of wear on them now.Try useing Marvel Oil throgh itWhy does a diesel burn oil?
That old of a diesel will always burn oil. The more miles the more oil. 100 miles per quart likely would be about it. Your rings are worn out. The engine has oil in the crankshaft which is splashed on the walls of the piston. The rings are suppose to wipe 99.9% of that oil off and put it back down in the pan. In your case some of it stays on the piston walls and is burned in the combustion process. Also your valve guide seals are likely leaking and so you are getting oil from your intake valve guide seals also. Replace the rings and the valve guide seals and you are on your way. I don't remember whether that engine has piston liners. If it does, then your over haul would have to include liners also. so liners, rings and valve seals. Tearing down, replace the bearings also.
rings, valves or crankcase ventilation. have a compression test done, as others said it might be time for rebuilding or retiring. It is about 9 years old now
Yer kidding, right? Sure was funny.
Turn it off and rebuild the engine. The poor thing is tired and needs a rest and rebuild.