Abstract: The microstructure and morphology of graphene A produced by arc method andgraphene B produced by redox methodwere characterized using field emission scanning electron microscopy, X-ray diffraction, atomic force microscopy, Fourier transform infrared spectroscopy, and other methods to investigate the effect of two graphene as additives on the anti friction and anti-wear properties of heavy-duty diesel engine oil CK-4 15W-40. Using a four stroke diesel engine bench test to evaluate the improvement effect of adding graphene on fuel economy of oil products. The results of the four ball machine friction test showed that the introduction of both graphene can achieve anti friction and anti-wear effects. After adding graphene A, the wear spot diameter decreased by 20.89% and the friction coefficient decreased by 35.58%; After adding graphene B, the wear spot diameter decreased by 13.08% and the friction coefficient decreased by 19.23%. The fuel economy evaluation results showed that adding graphene A to heavy-duty diesel engine oil under high-speed conditions can reduce the effective fuel consumption rate by 1.0% to 2.5%.

Key words: diesel engine oil, graphene, anti-wear and friction, fuel economy, lubrication