Why does the oil in an engine need to be changed at regular intervals?

Engine oil needs to be changed at regular intervals to ensure optimal engine performance and longevity. Over time, oil breaks down due to heat, oxidation, and contamination from dirt and debris, losing its lubricating properties. This degradation can lead to increased friction, wear on engine components, and potential damage. Regular oil changes help maintain proper lubrication, reduce engine wear, and improve overall efficiency.