1. The piston cylinder liner is not well sealed, the engine oil escapes upward, enters the combustion chamber for combustion, and the exhaust emits blue smoke.

2. For supercharged diesel engine, the supercharging pressure is low due to low load and no load. It is easy to cause the sealing effect of the supercharger oil seal (non-contact type) to decline, and the engine oil rushes into the supercharging chamber and enters the cylinder with the intake air.

3. Part of the engine oil flowing up to the cylinder is involved in combustion, part of the engine oil can not be completely burned, and carbon deposits are formed at the valve, air inlet, piston crown, piston ring, etc., and part of the engine oil is discharged with the exhaust.

4. When the oil in the supercharger chamber accumulates to a certain extent, it will leak from the joint surface of the supercharger.

5. It is also a very significant hazard that long-term low load operation will lead to more serious consequences, such as increased wear of moving parts, deterioration of engine combustion environment, etc., leading to early overhaul period.