The main reasons for high engine oil consumption are as follows

If the engine oil consumption is excessive, the cause should be carefully investigated and eliminated to ensure the normal operation of the engine. The main reasons for high oil consumption are as follows:
① Oil leakage. Leakage from the front crankshaft oil seal of the engine is a common fault. The crankshaft oil seal is a skeleton rubber oil seal, and leakage occurs due to installation and quality issues of the seal. It is recommended to change the installation method and use imported front crankshaft oil seals or those supplied by the manufacturer. The changed installation method is: disassemble the oil seal seat, install the oil seal, then assemble the engine, taking care not to damage or misalign the front end of the crankshaft against the oil seal, otherwise, the oil will still leak even after replacing the seal.
② Oil leakage at the compressor end of the turbocharger. Some users do not maintain the vehicle as required, causing severe clogging of the air filter, resulting in excessive workload and pressure drop from the air filter to the intake pipe. This pressure drop causes leakage at the compressor end of the turbocharger. Therefore, attention should be paid to cleaning and replacing the air filter element to ensure smooth intake. Some users, due to improper use of the turbocharger, aggressively rev the engine in the morning start-up or before shutting off, which easily damages the turbocharger oil seal, causing oil leakage and increased oil consumption.
③ Overfilling of engine oil. Excessive oil added blindly causes high pressure in the crankcase, leading to leaks in various parts. Therefore, when adding oil, it is best to fill it slightly above the middle between the upper and lower limits on the dipstick.
④ Air filter blockage causing excessive oil consumption. Due to neglect in cleaning and replacing the air filter during use, the safety filter element becomes blocked by water and oil contamination, causing poor air intake. Crankcase exhaust gases and oil are heavily drawn into the cylinder, resulting in excessive oil consumption. It should be noted that the vehicle's outer air filter element should be replaced every 12,000 km during secondary maintenance, and the inner safety filter element should be replaced every six months. The air filter element should be cleaned during each maintenance. For engineering vehicles, maintenance intervals should be shortened according to usage conditions.
Shorten maintenance intervals accordingly.
⑤ Using engine oil grades that do not meet requirements. Choosing ordinary diesel engine oil with too low viscosity can also cause excessive oil consumption and easily lead to early wear and burning of the bearing shells. Please do not use ordinary diesel engine oil.
⑥ Blockage of the oil-gas separator is also a cause of excessive oil consumption. The crankcase exhaust pipe connects to the oil-gas separator, which helps maintain good lubrication performance of the oil, extends the oil's service life, keeps the surfaces of lubricated friction pairs in good condition, reduces wear and corrosion of parts, maintains the pressure inside the engine body equal to the external atmospheric pressure, reduces oil leakage, recycles mixed exhaust gases, improves engine economy, and reduces environmental pollution. The crankcase ventilation system should be cleaned frequently during maintenance to prevent blockage.
⑦ Severe wear of the air compressor piston, piston rings, and cylinder wall causes oil to be discharged from the exhaust valve. When this fault occurs, oil in the air circuit causes severe damage to various valves. If oil is found in the water discharged from the air reservoir, it is best to replace the air compressor piston, piston rings, and cylinder to maintain normal clearances.
⑧ Early wear of the cylinder liner and gas blow-by are also causes of excessive oil consumption.