Oil-cooled engine

An oil-release space is formed along a lower side portion of a cylinder lateral and peripheral wall below an oil-cooling jacket. A reinforcing plate spans between the lower side portion of the cylinder lateral and peripheral wall and a bottom wall of a push-rod chamber below the oil-release space. The oil-release space is communicated with an oil outlet of an oil-return passage. Engine oil that has passed through the oil-return passage is released from the oil outlet into the oil-release space. The engine oil released into the oil-release space is guided by an upper surface of the reinforcing plate to drop from a led-out end on a rear side of the reinforcing plate onto a rear side space.