This lubrication system for a differential of a driven axle on an automotive vehicle includes a sump in which is located a crown wheel driven by a pinion, the crown wheel being fast in rotation with a carrier, and a main lubricant tank having an inlet port and at least one outlet port. Rotation of the crown wheel causes lubricant to be transferred from the sump to the main tank via the inlet port, and the outlet port allows the lubricant to pass from the main tank to the sump. The lubrication system includes an auxiliary lubricant tank located in the sump, adapted to be filled in with lubricant by rotation of the crown wheel, and an arrangement to convey lubricant from auxiliary tank to a lubricant needing portion of the differential.