If a vehicle's oil is not changed as required, the filter stops working and dirt accumulates in the engine making the oil lose its lubricating qualities. As a result, the metals in the vehicle come into contact, making them wear.
Oil is important for the smooth functioning of the various systems in the vehicle. For example, it lubricates the pistons to allow them function properly in the cylinder. Without oil, a friction is created between the metals making them weld together and eventually seizing up the engine. Even though today's vehicles do not burn oil as vehicles in the past, it is advisable to change a vehicle's oil as recommended by the manufacturer.