A differential reducer for a motor vehicle, including: a differential mechanism including a ring gear; a reduction mechanism including a secondary pinion and a primary pinion; a crankcase including a first half-crankcase and a second half-crankcase, of which an internal transverse wall of each half includes three bearing seats, each internal transverse wall having first means for collecting and directing oil sprayed by the ring gear, which means turn in a first direction of rotation to the bearing seats; wherein each internal wall includes second means for collecting oil which is sprayed substantially transversally through rotation of the ring gear in a second direction of rotation.