What Causes Oil Inside the Throttle Body?

[Jace]

Oil inside the throttle body occurs because, during engine operation, some combustible air-fuel mixture can leak through the gap between the cylinder and piston rings due to pressure differences. If not vented in time, this can lead to excessive pressure inside the engine. Therefore, every engine is equipped with a crankcase ventilation valve, which allows excess combustible mixture to be expelled through the PCV (Positive Crankcase Ventilation) valve and recirculated back into the intake manifold to participate in combustion. The throttle body is a controllable valve that regulates air intake into the engine. After entering the intake pipe, the air mixes with fuel to form a combustible mixture for combustion and power generation. As a critical component of fuel-injected engine systems, the throttle body is located between the air filter (above) and the engine block (below), acting as the "throat" of the engine. The responsiveness of acceleration is closely related to the cleanliness of the throttle body.