A turbocharger (300) for an internal combustion engine (500) includes a
center housing (304) connected to a turbine housing (302) and a
compressor housing (306). A shaft (318) is in a bore (314) of the center
housing (304). An oil supply passage (328) is in fluid communication with
the bore (314). An oil drain passage (310) is in fluid communication with
a oil cavity (334) and the bore (314). A vent passage (330) is in fluid
communication with the oil cavity (334) and an internal volume (520) of
the internal combustion engine (500). Oil flow passes through the first
passage (328) and the drain passage (310) during operation of the
internal combustion engine (500). A first pressure of air (P1) in the oil
cavity (334) is about equal to a second pressure of air (P2) in the
internal volume (520) of the internal combustion engine (500).