Engine oil is needed to reduce part friction and ensure correct working temperature in the engine. After every certain amount of kilometres driven it is important to change engine oil and filters.
How often it is necessary to do that depends on manufacturers recommendations. However, a good default distance is 15 000 km. Additionally, some people may choose to simply change engine oil and filters every year.
Every other oil change it is recommended to also change other car filters: car interior and gas.
What happens if you don’t change oil? As time goes on engine oil becomes less resistant to high temperatures, various debri appear on engine parts, friction between parts increases. After a while seirous engine issues may develope.