Short answer: every 3,000 to 5,000 miles or 3 - 6 months depending on the type of driving you do.
Long answer: Oil change intervals varies with driving habits and type of vehicle. I’m assuming we share the goal to minimize the need for major auto repairs. If you’re driving 20 miles one way to work and 15 of those miles are on the highway, most vehicles should have the oil changed every 5,000 miles. If you’re like me, drive 8 miles to work, never go more than 2 miles without stopping, most vehicles should have the oil changed every 3,000 miles or every 3-4 months. If you ride the bus to work and only drive your car to run a few errands on the weekend, that is the hardest type of driving on an engine. You may need to change your vehicles oil every 3-6 months regardless of the mileage.