The lube base oil prepared by blending Iranian 4th vacuum cut and Daqing 4th vacuum cut succeeded with conventional treating processes was used for 40CC grade diesel engine oil production. The physical chemical properties of the diesel engine oil samples obtained from various blending ratios with same additive formulation were proceeded the crankcase simulation, oxidation stability and wear tests. The test results showed that the base oil prepared from more than 75m%Iranian 4th cut can meet the requirement of CC grade diesel engine oil.