The Effects of Crankcase Oil Viscosity on Engine Friction at Low Temperatures
With Euro III emissions standards requiring a 50% reduction in current diesel car emissions from January 1st 2000, there is a need to improve fuel consumption and thus reduce exhaust emissions. One of the ways this is being addressed is by the introduction of lower viscosity crankcase oils and by the use of friction modifiers within these oils. The resulting reduced engine friction contributes to improved fuel economy and should also aid engine cold start ability. To investigate the cold start abilities of different crankcase oils, a matrix consisting of six different oil formulations was tested at -20°C, - 25°C and -30°C in a two litre four cylinder diesel engine. The tests were conducted using a dynamometer, with the engine being driven by the dynamometer at nominal cranking speed for 30 seconds and then increased to cold idle speed for a further 30 seconds.