* Hydraulic Pressure: The primary function is to provide hydraulic pressure to keep the lifter firmly against the camshaft lobe. This maintains consistent valve lash (clearance) and prevents valve train noise (especially clatter).
* Lubrication: The oil lubricates the moving parts within the lifter itself, reducing friction and wear.
* Cushioning: The oil acts as a cushion, absorbing shocks and vibrations from the camshaft. This helps prolong the life of the valve train components.
In short, the oil in a hydraulic valve lifter is essential for its proper operation and the longevity of the engine's valve train.
