Biodiesel fuel is attracting interest as an alternative fuel as environmental pollution increases and fossil fuel supplies diminish. Biodiesel is not only cleaner than petro-diesel, but also has high degradability and excellent lubricity. Since biodiesel has very low sulfur content (0.002 wt. %), it is environmentally friendly. The effect of a biodiesel additive in a diesel engine fuel system for reducing pollutant emission and wear characteristics was studied experimentally. Analysis was performed in two steps. First, the injection of biodiesel into the diesel engine channel was simulated. Second, tribological experiments were performed using the ball-on-ring contact method. The wear scar diameters and wear surfaces of the tribopairs were then analyzed. Wear experiments showed that a small addition of biodiesel to pure petrodiesel reduced friction and wear under boundary lubrication considerably.