<div class="htmlview paragraph">A low ambient temperature increases wear and fuel consumption in vehicle engines. The startability of the engine and the start-up of lubrication are highly dependent on the type of engine oil (mineral, semisynthetic, synthetic), whereas fuel consumption depends more on the engine type and driving conditions.</div> <div class="htmlview paragraph">The research work in a special cold chamber equipped with a powerful cooling system has so far involved three gasoline engines and two diesel engines. One gasoline engine was also tested in combination with an all-mechanical transaxle. Tests were carried out within the temperature range of +20…−30 °C using different engine lubricants in order to evaluate both lubrication during the initial start-up and fuel consumption during a test period of 30 minutes. Engines were run under both constant and cyclic load. Effects of auxiliary electrical block and oil sump heaters were also studied.</div> <div class="htmlview paragraph">For the same lubricant viscosity class, the camshaft oiling time was reduced as much as by 50 % by using synthetic oil instead of mineral oil. The startability was also improved with synthetic oil, though the oil type had only a minor effect on cranking speed. Friction was lower but compression work (pressure) higher with synthetic oil compared to mineral oil.</div> <div class="htmlview paragraph">The electric block heater aided considerably the starting of the engine, but flow properties of the engine lubricant are also important when using a block heater, because the heater does not normally warm up the sump oil.</div> <div class="htmlview paragraph">Lowering the test temperature from +20 to −25 °C increased fuel consumption by 4 - 9 % for the diesel engines and by 5 - 22 % for the gasoline engines over the test period of 30 minutes. The oil type had only a minor effect on fuel consumption. However, synthetic oil reduced friction losses in all-mechanical transmission considerably. The use of the block heater was found to be profitable for starting, lubrication and fuel consumption both in the gasoline and diesel engines.</div>