Oil pan for internal combustion engine

An oil pan for internal combustion engine comprising an upper portion to be attached to the bottom portion of a cylinder block directly or through an adaptor plate and a lower portion provided on the bottom of the upper portion, in which a baffle plate is formed integrally downward of said upper portion and an oil supplying means for supplying sucked oil to respective portions of the internal combustion engine is provided, said upper portion comprising side walls connecting said cylinder block with said lower portion and said baffle plate, the baffle plate comprising said sucking portion which is said oil supplying means provided substantially in the center and an inclined portion which is inclined downward toward said side wall with said sucking portion as its vertex, communicating opening portions being formed near said side walls of the inclined portion to communicate said cylinder block with said lower portion,

• wherein:
• a plurality of tightening holes for fastening the oil pan to a cylinder block with tightening means are provided in the top portion of the side wall of said upper portion,
• the tightening holes are located between respective cylinders along the arrangement direction of the cylinders formed in the cylinder block, and
• longitudinal ribs are formed vertically at positions corresponding to the positions of the tightening holes on the inner side of said side wall while the longitudinal ribs are inclined from the top end of said side wall to said baffle plate.