The invention relates to an internal combustion engine having inline type cylinders in a cylinder block (1) and a crankcase (2). The crankcase (2) includes separating walls (8) between cylinders with crankshaft bearings (11). The two sides of each cylinder in the crankcase (2) are respectively provided longitudinal oil distribution channels (18, 19). Pressure oil is conveyed to the crankshaft bearings (11) and other consumption devices via the oil distribution channels (18, 19). To ensure good oil supplying to all the consumption devices when the manufacturing cost is lowest, the two oil distribution channels (18, 19) are connected with each other through a transverse channel (23) extending in the separating walls (8). The transverse channel (23) has been manufactured in casting of the crankcase (2). A portion, connected to the oil distribution channels (18, 19), of a cross section of the transverse channel (23) is roughly circular and is flat in the transverse center (25).