Q My diesel-engined Land-Rover is
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parked overnight in the open all the year round and I frequently have trouble starting the engine in cold weather. In winter the temperature of the engine lubricant never reaches the optimum recommended by the oil company because it is overcooled by the oil cooler.
have ordered a cooling system immersion heater operated from the mains for winter use, but consider that an oil heater would be preferable as a means of overcoming my starting problems. Do you agree with this view and could you suggest a way in which the running temperature of the oil could be increased in winter?
AA cooling system immersion heater should be more effective in providing easier starting than an oil-sump immersion heater. The main cause of drag when an engine is cold is the high viscosity of the oil on the cylinder/piston surfaces, and warming the coolant should thin-out the oil film more quickly than by applying the same amount of heat to the sump oil. The heat path from the water to the pistons is much shorter than the heat path from the sump and this should more than compensate for the larger amount of fluid to be heated. Some heat would also be transferred to the cylinder head and combustion chamber. It is recommended that an oil/ water heat exchanger should be incorporated in the cooling system on the engine side of the thermostat to overcome the oil overcooling problem: it would also obviate overheating of the oil. A heat exchanger would give rapid warming-up of the oil and if employed in conjunction with thermostatically operated radiator shutters or a manually operated blind it would enable a near-optimum oil temperature to be maintained at all times. Accurate temperature control of the oil and water should increase the life of the engine and improve fuel consumption.