Abstract:In order to improve the tribological performances of diesel engine oil CD+/10W40 used in heavyloaded equipment,three kinds of oilsoluble organic Mo additives,molybdenum dialkyldithiophosphate (MoDDP),molybdenum dialkyldithiocarbamate (MoDTC) and aminemolybdenum (MoA),were added in the diesel engine oil.Friction and wear properties of the additives were tested by SRV frictionwear tester,the wear morphologies and elements were analyzed by laser microscope,SEM,EDS and XPS,and the frictionreducing and antiwear mechanism of the additives were studied.The results show that different kinds of organic Mo additives all can make the friction coefficient decrease,but they have different frictionreducing and antiwear effect in the diesel engine oil.MoDTC has the best frictionreducing and antiwear performance,which can reduce the friction coefficient and wear volume by approximately 533% and 269% respectively when adding mass fraction of 08% MoDTC in the diesel engine oil.While MoA instead increases the wear volume.The mechanism analysis show that the chemical reaction and deposition film containing MoS2,MoO3 and some other compounds from the decomposition of MoDDP and MoDTC are formed in the friction surface to decrease the friction and wear during the tribological process,but abrasive particles rather than tribological protection films are formed by MoA,hence the wear is increased.