Method for controlling the lubricating oil dilution of an internal combustion engine and device for monitoring and reducing this oil dilution

The present invention relates to a method for controlling the lubricating oil dilution - in volume percent - of an internal combustion engine. Furthermore the invention relates to a device for monitoring and reducing this oil dilution. It is an object of the present invention to provide a method, which enables technologies aiming at reduction of soot and NOx emissions, namely control strategies making use of in-cylinder post injection(s) required for vehicels equipped with particulates filter or lean NOx trap. Another object of the present invention is to provide a device for monitoring and reducing the oil dilution. According to the present invention and with respect to the first object a method is provided comprising the following steps (a) monitoring the oil dilution ratio by calculating and/or estimating the so-called oil dilution state from measured operating parameters, and (b) reducing the oil dilution ratio by promoting the evaporation of the liquid contaminates - such as water, glycol and in particular the light hydrocarbon fuel components mixed with the lubricating oil - by elevating the temperature of the diluted lubricating oil, and/or promoting the partial combustion of the diluted lubricating oil by increasing blow-by gas flow from crankcase to engine cylinder during fuel cut off in deceleration.