What is the most likely cause of low oil pressure in a warm engine?

Low oil pressure in a warm engine is often attributable to factors that affect the circulation and retention of oil within the engine. While leaky main bearing seals can contribute to oil pressure issues, they typically result in visible oil leaks rather than just low pressure readings.

The most likely cause of low oil pressure in a warm engine is a worn oil pump. As the oil pump ages, it may lose its ability to maintain the necessary pressure, especially as the oil thins out when warmed. High temperatures reduce the viscosity of the oil, which can exacerbate the problem. A worn oil pump cannot pump oil efficiently enough to maintain adequate pressure, so this situation becomes especially critical when the engine is warm.

Furthermore, while factors such as leaking gaskets or a dirty oil filter can contribute to various engine performance issues, they do not have as direct an impact on oil pressure specifically as a worn oil pump does. A dirty oil filter can restrict oil flow, potentially leading to low pressure, but this effect is generally less pronounced in a warm engine scenario. Thus, the integrity of the oil pump is crucial for maintaining proper oil pressure in a warm engine.