1. Method for controlling a powertrain comprising an electro-mechanical transmission mechanically-operatively coupled to an internal combustion engine and an electric machine and a hydraulic control system providing a first, base cooling flow to said electric machine and selectively providing a second, active cooling flow to said electric machine, said transmission adapted to selectively transmit mechanical power to an output member, said method comprising: providing said base cooling flow to said electric machine through a first hydraulic circuit; and selectively providing said active cooling flow to said electric machine through a second hydraulic circuit, comprising: monitoring a temperature of said electric machine; determining a cooling flow requirement for said electric machine based upon said temperature of said electric machine; comparing said cooling flow requirement to said base cooling flow; and providing said active cooling flow based upon said comparing.