a single horizontal cylinder , small refrigeration compressor has a lubrication arrangement which includes a recess on the cylinder block above the cylinder bore which collects oil that drains from the lower end of the motor . a supply passage extends downward from said recess and opens into the cylinder bore near its midpoint . the piston has an elongated shallow groove on the interior between head and skirt lands which is connected to the passage during a major portion of the piston stroke to receive oil from the recess . drain passage means are provided on the piston to allow oil to flow out of the groove at a lesser rate than it is supplied by the supply passage from the recess .