Why is there oil in Hino engine gear box?

First of all, cars often drive at a low speed. At this time, the crankcase temperature is low, and the injection amount is large when the engine is running at low speed, and some partially burned gasoline fuel enters the crankcase, resulting in low-temperature sludge. Secondly, when the crankcase ventilation valve is partially or completely blocked by oil impurities, sludge, etc. Waste and steam in the crankcase cannot be discharged in time, resulting in sludge. Thirdly, in order to improve fuel economy, some high-performance direct injection engines on the market adopt a technology called lean combustion to reduce fuel injection. China's inferior oil products and lean oil combustion make the exhaust gas entering the crankcase produce sludge due to the high content of nitrogen oxides.

In addition, inferior engine oil and gasoline can also cause sludge.