Abstract: On a lubricating oil fill line for an internal combustion engine, provided with an oil mist sediment tank installed in the fill area and designed to ensure the crank case ventilation, the oil flowing out of the oil mist sediment tank is recycled by the gravity force back to the crank case as return oil. This system has the following features: for the return oil is provided a return line from the oil mist sediment tank; the distal end of this return line relative to the sediment tank leads to the bottom area of a transfer tank especially designed to receive and recycle the return oil; a gas pressure is exerted at the overflow outlet of the overflow tank which corresponds to that to which the oil mist is submitted when back to the sediment tank. Such a facility permits to save space during the manufacture process.