An oil change is a routine maintenance procedure that involves draining old engine oil from a vehicle and replacing it with fresh, clean oil. This helps to lubricate the engine's moving parts, remove harmful contaminants, and prevent engine wear and tear. During the process, a mechanic will also replace the oil filter to ensure that the new oil remains clean and effective. Regular oil changes are essential to keep a vehicle running smoothly and can help extend its lifespan. It's typically recommended to get an oil change every 3,000 to 5,000 miles, depending on the make and model of the vehicle.