in a method and an apparatus for detecting a continuous ingress of fuel into the lubricating oil of an internal combustion engine , that is to say oil dilution , in particular of a motor vehicle during cold starting , there is provision , in particular , for the continuous ingress of fuel to be detected by means of a lambda control . the continuous ingress of fuel is preferably determined using the outgassing of fuel from a crankcase of the internal combustion engine , wherein the depletion is based on adaptation values of the lambda control .