Why does engine oil turn black after usage in a motor engine?
basically carbon from blow-by turns the oil black.it can also be caused from the oil cooking. i would prefer that a diesel burns some oil.this keeps bad injectors from washing cylinder walls and causing abnormal wear.it also keeps the engine from wearing and scoring the cylinders,because diesels are designed with close tolerances.it gives just a little extra lube between cylinder walls and piston.it also helps to isolate combustion chamber temps,so when it burns a lil oil and combined with a piston cooling system,like used in a cummins,itll help to reach that 1 million mile mark with no problems.
