What is a common symptom of low engine oil?

A common symptom of low engine oil is an engine knocking noise. This occurs because oil is responsible for lubricating the engine's moving parts. When the oil level is low, there may not be sufficient lubrication, leading to increased friction between components. This friction can cause the engine parts, such as pistons and bearings, to produce a knocking or tapping sound as they struggle to operate smoothly.

While poor fuel efficiency can be related to various factors, it is less directly tied to low oil levels compared to the immediate mechanical distress evidenced by knocking. Frequently stalling may indicate issues with fuel delivery or ignition rather than oil levels, and intense vibration during driving is generally more associated with balance or alignment issues rather than oil levels. Thus, the specific nature of engine knocking illustrates the critical role that oil plays in engine health and operation.