What happens to engine oil when it becomes hotter?

When engine oil becomes hotter, its viscosity decreases, meaning it becomes thinner and flows more easily. This reduction in viscosity can lead to lower oil pressure at idle. Lower viscosity allows the oil to circulate more freely through the engine components but can also mean that under lower engine RPM conditions, like idling, the oil pressure may not be maintained at the same level as it would be with cooler oil.

As oil heats up during engine operation, the molecular structure of the oil is affected, leading to these viscosity changes. In a hot engine, if the oil loses too much viscosity, it may not provide optimal lubrication, which can lead to insufficient oil pressure, especially when the engine is idling. This understanding of how temperature affects oil viscosity is crucial in ensuring proper engine performance and longevity.