The present study focuses on the use of lubricating oil as a coolant for electrical motors. Oil is introduced at each side of a 40 kW test machine to directly cool the stator coil end-windings. An experimental setup has been implemented to test different oil injection patterns. The influence of the oil flow rate, rotation speed and oil temperature has been investigated (40 L/h <Qv < 360 L/h, 50 degrees C < T-oil < 75 degrees C, 0 < omega <4600 rpm). The results show a strong dependence of the flow rate on global cooling performance, whereas the effect of rotation speed is smaller but can affect local temperature. (C) 2014 Elsevier Ltd. All rights reserved.