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.