To verify the feasibility of regenerated lubricating oils,a bus diesel engine using 15W40 oil was used as the research object,the tribological properties i.e.carrying capacity,friction reducing and antiwear ability,and wear surface morphology were studied during the using period of lubricating oil.The results show that the regenerated lubricating oil shows almost the same carrying capacity and friction reducing ability as the original oil.During the 3 months used cycle,along with the time,there are almost no change on the carrying capacity and the friction reducing ability of the original and the regenerated lubricating oils,but a little reduction of antiwear ability of regenerated lubricating oil during the third using month.The wear surface of the ball lubricated by regenerated lubricating oil shows relatively long,deep furrows,relatively wide scratches,and relatively large shedding area compared to that of original 15W40 oil during different using stage,which indicates that the regenerated lubricating oil has relatively poor antiwear performance.