A system and method are provided for supplying oil at different temperatures to different locations within a wind turbine gearbox, wherein oil is pumped from a common oil sump to the different locations via a common header. The different gear box locations are divided into at least two groups, wherein each of said groups receives inlet oil at a respective inlet oil temperature. A first temperature control device is disposed between the common header and the first group, and a second temperature control device is disposed between the common header and the second group of gearbox locations.