Results from the tests on a high-speed back-to-back stand (vt= 70 m/see = 13725 ft/min) show the influence of the separationof lubrication and coolingoil supply on the geartemperatures (scuffing load capacity) and efficiency. The gear mesh is only given a minimum oil flow rate necessaryfor lubrication of the working tooth flanks. Cooling is provided by spraying oil onto the inner surfaces of the rims. This leads to a reduction of the total oil flow rate of up to 60% compared to the currently recommended flow rates. In spite of the reduced total oil flow rate the temperature level of the gears can be kept low and the efficiency slightly increases due to reducedhydraulic losses in the gear mesh.