Abstract: A method for improving the oil drain interval, fuel and energy efficiency of heavy duty geared machinery by lubricating said apparatus using a lubricating oil composition comprising as base oil about 20 to 75 wt % PAO 2 to 10, about 5 to 40 wt % PAO 150-1000, about 10 to 40 wt % PAO 20-100, about 5 to 20 wt % of one or more polyol ester or dibasic acid ester having a kinematic viscosity of between about 2 to 5 mm2/s at 100° C. mm2/s and further containing an effective amount of at least one gear oil additive, said lubricating oil composition having a kinematic viscosity at 100° C. between 9 and 12.5 mm2/s, and exhibiting a traction coefficient value (100°C./30 SSR value) of 0.0197 or less, a Brookfield viscosity at ?40° C. of about 26,000 cP or less a CCS viscosity at ?25° C. of 4200 cP or less, a flash point of 220° C. or higher and a NOACK volatility of 15% or less.