METHOD OF DETERMINING FUEL EVAPORATION FROM AN ENGINE OIL SUMP

A method of determining the total evaporation rate of fuel from an oil sump of an engine comprising: a) defining for said fuel, a plurality (n-1) of zones, each zone comprising a separate temperature range, and corresponding to a particular fuel constituent portion; b) determining or estimating the mass of said particular fuel constituent portion present in the sump for each zone; c) for each zone, determining an evaporation rate based on oil temperature; and the corresponding mass determined in step b); d) summing the evaporation rates for each zone from step c) to provide said total evaporation rate.