If you own a car, it's important to know how often to change your car oil. Depending on the make of your vehicle, you should change your oil every 6,000 to 9,000 miles or about every 6 months, whichever comes first. However, it's best to consult your car's owner’s manual for the specific recommendations. Changing your car oil regularly will help keep your engine running smoothly and prolong the life of your vehicle.