A composite oil pan for a work vehicle engine and a method of forming the composite engine oil pan include forming a sheet of metal into a first pan and open molding a fiber-reinforced polymer resin onto the first pan forming a second pan. The first pan has a first bottom wall and first peripheral walls extending from edges of the first bottom wall to define a sump, the first peripheral walls terminating in a first peripheral flange. The second pan has a second bottom wall and second peripheral walls abutting the first bottom wall and the first peripheral walls, the second peripheral walls terminating in a second peripheral flange. The first pan defines a thin metal structure with an inner surface extending across the first bottom wall, first peripheral walls and first peripheral flange; the second pan reinforces the first pan without abutting the inner surface.