Modern automotive and industrial engines require high efficiency and long-term performance. Engine oils play a crucial role in ensuring smooth operation, reducing wear, protecting against corrosion, and enhancing overall engine efficiency. However, the base oil alone is often insufficient for optimal performance under extreme operating conditions. Therefore, modern engine oils are formulated with various additives that enhance stability and protect engine components. The article provides a detailed examination of the mechanisms of these additives and their effects on engine performance, offering practical insights for selecting and optimizing engine oils for modern vehicles and industrial applications.