The primary function of an oil relief valve is to maintain the oil pressure within a specified range. It opens when the oil pressure exceeds a predetermined level, allowing excess oil to bypass the system and return to the oil sump.

By preventing excessive oil pressure, the relief valve protects sensitive engine components, such as bearings and seals, from damage. High oil pressure can lead to leaks, oil starvation, and even catastrophic engine failure.

The oil relief valve helps ensure that oil is distributed evenly throughout the engine. By regulating pressure, it allows for consistent oil flow to critical components, enhancing lubrication and reducing wear.

In some cases, the oil relief valve can help manage engine temperature. By allowing excess oil to bypass the system, it can prevent overheating of the oil, which can degrade its lubricating properties.

The most common type, these valves use a spring mechanism to control the opening and closing based on oil pressure. When pressure exceeds the spring's preset limit, the valve opens to release excess oil.

These valves are designed to allow oil to bypass the filter when it becomes clogged, ensuring that the engine continues to receive lubrication even if the filter is obstructed.

Some modern engines use variable relief valves that can adjust their opening pressure based on engine conditions, providing more precise control over oil pressure.