Several civilian vehicles in China operate in urban traffic conditions and have their motor oil changed every 5,000 km. This study investigates the variations in oil properties after servicing at 5,000 km, based on systematic road tests (including a repeated test, a parallel test, and a new vehicle test). The physicochemical properties, changes in components, oxidation stability, detergent-dispersant performance, and tribological properties of motor oils were analyzed. The results showed that the total acid number (TAN) of oils increased with t...
