Do you let your car idle to "warm it up" before going out in the cold to drive it away? If so that will cause gasoline smelling oil. The engine warms up so slowly when idling that gas condenses on the cylinder walls and runs down past the rings, contaminating the oil (and washing the oil off the cylinder walls). I've had mechanics tell me they can tell whether a car sat and warmed up 10 minutes before being driven or not, based on the wear on the cylinder walls. Don't know whether I really believe it or not.