Zinc dialkyldithiophosphate (ZnDTP) has been the most widely used as lubricant additives in the engine, but ZnDTP can easily cause sludge and catalyst poisoning. Therefore the development of alternative additives has been proceeded. Molybdenum dithiocarbamate (MoDTC) as a friction modifier is incorporated into low-viscosity engine oils and forms tribofilm containing molybdenum disulfide (MoS2). However, the synergistic effects of ZnDTP and MoDTC have not been much clarified, and it is in the research phase. In this study, friction and wear properties of the boron cast iron and CrN (chromium nitride) used for piston sliding parts are investigated by using a block-on-ring type sliding tester in lubricating oils with ZnDTP, MoDTC and anti-wear agents containing sulfur. As a result, the friction coefficient of MoDTC and ZnDTP with primary alkyl containing lubricant was higher than that of MoDTC containing lubricant. And, the friction coefficient of MoDTC and ZnDTP with secondary alkyl containing lubricant was lower than that of MoDTC containing lubricant. The friction coefficient of the lubricant with MoDTC and anti-wear agents containing sulfur was lower than that of MoDTC containing lubricant. Synergistic effects of additives were investigated with the X-ray Photoelectron Spectroscopy (XPS) analysis.