The positive crankcase ventilation valve releases exhaust gas and unburned fuel from the engine block into the intake manifold. All engines allow some exhaust gases, unburned fuel and oil to ...

“As engine technology and fuel technology have evolved, the environment in the crankcase has changed,” says Stede Granger, Shell Lubricants. Twenty-five years ago, fuel sulfur levels hovered ...

The report mentions that the failure could be traced to a damaged piston inside the engine, which allowed the crankcase to become pressurized and lose oil.