Abstract: An automatic transmission lubricating oil based on poly-α-olefins was trial-manufactured and then added to the automatic transmission of the bus for a 60,000-kilometer driving test to detect the trend of the oil performance change with the driving mileage. The crankcase simulation test was conducted; the viscosity and wear resistance under high temperature conditions were investigated. The test results showed that with the increase of driving mileage, the kinematic viscosity, viscosity index and maximum no-bite load value of the trial oil first decreased and then stabilized. The results of the crankcase simulation test had certain correlation with the driving test results, but with large difference. The results of the crankcase simulation test can`t be used to accurately predict the driving test.

Key words: automatic transmission oil, poly-α-olefin, driving test, simulation test