To evaluate the impact of various proportions of erucamide and N-phenyl-α-naphthylamine on grease’s tribological performance for roller bearings, lithium complex grease (LCG) and polyurea grease (PG) were prepared with erucamide and N-phenyl-α-naphthylamine proportions of (0,0), (0,3), (1,2), (2,1), and (3,0). An investigation was conducted into the microscopic structures of the ten greases and their effects on the friction coefficients and wear scars of GCr15 steel. These findings were validated through bearing friction torque tests. The results indicate that the addition of 2 wt. % erucamide and 1 wt. % N-phenyl-α-naphthylamine to PG/LCG significantly enhances their tribological properties and reduces friction torque, with PG exhibiting superior performance. This enhancement was attributed to the synergistic interaction of erucamide and N-phenyl-α-naphthylamine with the lamellar thickener within PG. Erucamide contributed to friction reduction, while N acted as an antioxidant.