Changing the engine oil and filter is important for the proper functioning and longevity of your vehicle's engine. Here are some reasons why:

1. Lubrication: The engine oil provides lubrication to the moving parts of the engine. This reduces friction and wear on the engine's components, which can lead to damage and decreased performance over time. Old or dirty oil can become thick and lose its lubricating properties, making it less effective at protecting the engine.

2. Cooling: The engine oil also helps to cool the engine by carrying heat away from the engine's components. As the oil circulates through the engine, it absorbs heat and transfers it to the oil cooler or the engine's oil pan. Over time, the oil can break down and lose its ability to absorb heat, which can cause the engine to overheat.

3. Contaminants: The engine oil also acts as a filter, capturing dirt, debris, and other contaminants that can enter the engine. Over time, these contaminants can build up and clog the oil filter, reducing the flow of oil to the engine and causing damage.

Regularly changing the engine oil and filter helps to ensure that your vehicle's engine remains properly lubricated, cooled, and free from contaminants. The exact interval for oil changes may vary depending on the vehicle make and model, driving conditions, and oil type, so it's important to follow the manufacturer's recommendations for your specific vehicle.