Our final triple-threat test involved replacing the 10W-40 conventional oil with ultralight 0W-5 race oil. Of course not an ideal long-term street oil, this race blend was designed for use by drag racers looking for every last horsepower.On a near-stock 4AGE Toyota engine, the lightweight synthetic oil showed impressive gains, especially considering the original power output. In fact, the Lucas Oil upgrade improved the power output more than the header or air intake system tested previously on this application. The synthetic oil upgrade increased the 4AGE's power output from 108 hp to 114 hp, with the largest gain of 8 hp occurring just past 7,000 rpm. The oil alone improved the power output of this twin-cam Toyota engine by 7.5 percent.