During an oil change service, a technician drains out your engine’s old, dirty oil and replaces it with fresh oil that meets your vehicle manufacturer’s specifications. They also replace the oil filter, which traps dirt and metal particles so they do not circulate through the engine. Most shops perform a quick visual inspection under the hood, check fluid levels, and may top up items like washer fluid or coolant if needed. Many will also perform a basic inspection of belts, hoses, and possibly your tires and lights to alert you to any obvious issues. Overall, the goal is to keep your engine properly lubricated, running cooler, and protected from premature wear.