The article presents the results of experimental investigation of oil temperature control system as means of forced diesel engine (cylinder diameter - 150 mm) cold start characteristics improvement. The effect of operating conditions and oil temperature control system design on the thermal state and the cold start characteristics of the diesel engine was determined experimentally (in "climate" chamber). It is proved, that the application of this system and coolant heater with the recommended design parameters and operating modes, ensures the diesel compliance with the requirements of normative and technical documentation, and allows increasing oil temperature in the main oil line (without coolant heating) by -10...23 degrees C, in the crankcase -by 5...10 degrees C, the average temperature of the diesel engine -by 7...8 degrees C, before the start, providing a guaranteed engine start at ambient temperatures of -25 degrees C within 5...8.5 minutes, at -50 degrees C - within 21...28 min. The impact of the diesel engine start with coolant heater and oil temperature control system on the wear of engine parts is analyzed. It was established experimentally, that the main power and fuel consumption parameters of the engine meet the technical requirements. The condition of the engine parts friction surfaces, to which oil is supplied under pressure (crankshaft and camshaft, oil pump, etc.), is normal. This confirms the satisfactory condition of these parts lubrication in the cold start-up process. (C) 2016 The Authors. Published by Elsevier Ltd.