Why is there engine oil in the intake pipe of the Haval H6?

[HarperLee]

Haval H6 intake manifold has engine oil due to the following reasons: 1. Prolonged engine idling; dirty air filter; clogged or deformed crankcase ventilation system. 2. Clogged, leaking, or deformed turbocharger oil inlet and return pipes; coking of lubricating oil in the turbocharger's intermediate housing. 3. Cylinder wear causing piston ring blow-by; excessive flow resistance in the exhaust system. 4. Prolonged imbalance between intake pressure and the pressure inside the turbocharger bearing housing, leading to oil leakage from the turbocharger into the compressor due to pressure differential acting on the seals. 5. Excessive engine oil filling, which inevitably increases the lubricating oil content in the crankcase ventilation system, thereby causing lubricating oil to enter the intake pipe through the crankcase ventilation system.