A ring gear for a planetary gear set has an annular gear body with a first annular side and a second annular side concentric about a center axis. The first annular side defines a toothed periphery. The gear body may include an annular groove in the first annular side proximate a first axial side of the gear body. An axial flow passage section may extend axially into the gear body from the annular groove without intersecting the first and second annular sides. A radial flow passage section extends radially into the gear body from the second annular side to the axial flow passage section.