Abstract: A casing for the lubrication of a camshaft of an internal combustion engine for automotive vehicles is partially filled with lubricating oil to effect splash lubrication of cams carried by the camshaft and has at least one lateral overflow port to maintain the oil at a substantially constant level. The overflow port is configured so as to prevent removal of oil which is not in excess of the required amount as a result of the shifting of the oil due to a uphill or downhill inclination of the vehicle. According to a preferred embodiment, the overflow port has a horizontal lower wall which corresponds to the desired maximum level of oil when the vehicle is level and this lower wall is flanked by inclined walls which correspond to the desired maximum level when the vehicle is in uphill and downhill orientations, respectively.