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Partly competing objectives, as low fuel consumption, low friction, long oil maintenance rate, and at the same time lowest exhaust emissions have to be fulfilled. Diminishing resources, continuously reduced development periods, and shortened product cycles yield detailed knowledge about oil consumption mechanisms in combustion engines to be essential. There are different ways for the lubricating oil to enter the combustion chamber: for example as blow-by gas, leakage past valve stem seals, piston rings (reverse blow-by) and evaporation from the cylinder liner wall and the combustion chamber. For a further reduction of oil consumption the investigation of these mechanisms has become more and more important. In this paper the influence of the mixture formation and the resulting fuel content in the cylinder liner wall film on the lubricant oil emission was examined.

Reduction of fuel consumption and pollutant emissions are key factors in the current development of powertrains. Engine oil has proven to be an efficient lever for improving fuel economy. The full potential of a low viscosity lubricant could be achieved by a shift towards formulations with low viscosity, high volatility base oils. However, there is a concern that this might increase oil consumption and limit long oil drain intervals. This article deals with the engine lubricant contribution to oil and particle emissions. A series of 0W-12 oil prototypes have been evaluated both within laboratory measurements and on a modern turbocharged direct injection gasoline engine. Correlation between oil emission and engine oil properties will be presented. The impact of engine oil on particle emissions has also been investigated under different engine operating conditions.