An oil sump (10) is disclosed for a structural engine of an agricultural vehicle (1). The underside of the sump (10) is formed with a longitudinally extending downwardly concave tunnel (16) to accommodate a propeller shaft (30). The tunnel (16) divides the interior of the sump (10) into two oil trays (18a, 18b) arranged one on each side of the tunnel (16). Oil passages (20a, 20b) are cast into the sump (10) to connect the two trays (18a, 18b) to a common recirculation duct (24) that leads to the intake side of the engine oil pump.