An oil separation device includes an oil separator in a housing between a gas inlet and an outlet. An opening is formed at the longitudinal end of a gas-conducting channel connected to the gas inlet the end facing away from the gas inlet, and a throttle aperture movably mounted in the longitudinal direction of the gas conducting channel. The gas conducting channel and an outlet channel form an annular gap through which crankcase ventilation gases flow via a nozzle gap, and the housing has an additional opening to which a reference pressure can be applied on the throttle aperture side facing away from the gas conducting channel. The throttle aperture extends radially beyond the annular gap and has a seal region molded onto the edge that is sealingly arranged in a recess formed in the housing such that the throttle aperture fluidically separates the additional opening from the gas inlet.