Why do i need to change my engine oil and how often is it recommended?

Over time, new oil gradually loses its properties, particularly its ability to lubricate, protect and keep clean engine surfaces. The loosing rate of oil properties depends on many factors, the main ones being: engine design features, operating conditions, technical condition of the engine due to mileage, etc. The criteria for the choice of oil and its change frequency are set by the car manufacturer depending on mileage, service life and loads. For most modern cars, this is 15 thousand kilometers or once a year.