A pump, such as a vacuum pump, includes at least one housing and a motor and oil reservoir disposed within the housing. The pump housing can include a bottom exterior surface and one or more side and/or front exterior surfaces that extend generally up from the bottom exterior surface. An oil drain port can be positioned at or near the intersection of the bottom exterior surface and the side or front exterior surface. The housing can include an interior bottom surface that defines at least a portion of a drain passageway for the pump and can be fluidicly coupled to the oil reservoir. At least a portion of the interior bottom surface can be angled downward at an acute angle to the horizontal towards the oil drain port to improve the draining and replacement of oil in the pump.