Kia Orie engine just overhauled. What happened to the throttle suction?

When the engine is working, exhaust gas will be produced in the crankcase, which contains a small amount of oil mist, and some gas will be sent to the engine cylinder for combustion along with the pipeline of crankcase ventilation system through the intake manifold. The engine oil mixed with air enters the engine from the intake manifold through the throttle, so it is normal that some engine oil will remain on the throttle.