A rocker arm includes a follower which follows a first lobe of a camshaft and is mounted to a rocker arm body; a lock pin that is selectively moveable in a lock bore between a first position and a second position in order to prevent relative movement between the rocker arm body and the follower in one of the first position and the second position and to permit relative movement between the rocker arm body and the follower in the other of the first position and the second position; and a rocker arm oil passage in fluid communication with the lock bore for communicating oil therethrough to move the lock pin between the first position and the second position. The rocker arm oil passage is elongated in a circumferential direction relative to the lock bore.