Change the oil in an automobile by locating the oil drain plug, loosening and removing the plug, removing the oil fill cap, allowing the oil to drain into a drip pan and replacing the spent oil with fresh oil. During an oil change, you should also change the oil filter for the maximum benefit.
Before performing an oil change yourself, consult the owner's manual for the vehicle to see what type of oil the manufacturer recommends. Older models of car require a certain level of oil pressure to operate properly, and adding an oil with the wrong viscosity can cause damage to those vehicles' engines. You may need to jack up some vehicles to properly perform an oil change. Place wheel chucks, cement blocks or wooden posts behind the tires, and apply the parking brake to prevent the vehicle from rolling off of the jack while you are underneath.
Replace the oil filter with a fresh one rated for the mileage that you intend to drive until the next oil change during every oil change. Some makes and models have a shroud or cover on the underside of the engine that you need to remove in order to access the oil filter and drain plug. Remove the shroud by unscrewing or unclipping it from the frame of the vehicle.