If you find oil in your intake manifold, it's not something that should be ignored, but what has caused it isn't always clear. Here the most likely culprits.

The global market for Automotive Variable Intake Air Control Valves, valued at USD 6.9 billion in 2024, is projected to reach USD 9.1 billion by 2030, expanding at a CAGR of 4.5%.

The addition of variable valve timing made it possible to control intake valve timing for optimal performance. VVT-i can be seen as a high-tech adjustable cam sprocket.

The intake valve lift control system opens the valves only slightly to the “low lift” position, giving the 2.4-liter four-cylinder lump better economy under normal driving.

Thompson Lanzanova, Macklini Dalla Nora, Hua Zhao, Investigation of Early and Late Intake Valve Closure Strategies for Load Control in a Spark Ignition Ethanol Engine, SAE International Journal of ...

Stefan Gundmalm, Andreas Cronhjort, Hans-Erik Angstrom, Divided Exhaust Period, SAE International Journal of Engines, Vol. 6, No. 2 (June 2013), pp. 739-750 ...