1217230250 121723-0250 1-21723025-0 Ex400-5 6Rb1 Oil Radiator Core For Isuzu The oil radiator core with part number 1217230250, also designated as 121723-0250 or 1-21723025-0, is specifically crafted for the Isuzu Ex400-5 6Rb1 engine. Its function is to assist in regulating the temperature of the engine oil, thereby aiding in maintaining the engine's optimal performance levels.