This study presents a numerical investigation of an oil supply system for a hermetic reciprocating compressor used in household refrigerators. It is aimed to investigate the geometric parameters of the crankshaft affecting the mass flow rate of the lubricant released from the outlet of the crankshaft. The change of the mass flow rate from the outlet of the crankshaft associated with helix-screw indicates that with reducing the screw pitch, the mass flow rate decreases. An important finding is that increasing the depth of the helical channel plays a more significant role than increasing the width of the helical channel. The mass flow rate increases when the distance between the suction hole of the crankshaft and the oil sump bottom increases. The wall thickness of the crankshaft does not significantly affect the mass flow rate whereas it plays a crucial role in formation of the vortices around the crankshaft. (C) 2014 Elsevier Ltd and IIR. All rights reserved.