A cooling system for an internal combustion engine, the cooling system comprising: a high-temperature cooling circuit piping (44, 46, 48) including high-temperature cooling circuit connection ports; a low-temperature cooling circuit piping (64, 66) including low-temperature cooling circuit connection ports; and a two-stage charge air cooler unit (50; 504, 506) including a first cooling stage with first cooling stage connection ports (43; 222, 224, 226, 228) and a second cooling stage with second cooling stage connection ports (61; 230, 232, 234, 236), the first cooling stage providing a first heat transfer performance, and the second cooling stage providing a second heat transfer performance different from the first heat transfer performance, wherein the first cooling stage connection ports (43; 222, 224, 226, 228) and the second cooling stage connection ports (61; 230,232, 234, 236) have the same geometry and are symmetric to each other with respect to a plane perpendicular to a flow direction of charge air, and wherein the two-stage charge air cooler unit is configured to be mounted in the cooling system in a first mounting position, in which the first cooling stage is connected to the high-temperature cooling circuit connection ports via the first cooling stage connection ports (43; 222, 224, 226, 228) and the second cooling stage is connected to the low-temperature cooling circuit connection ports via the second cooling stage connection ports (61; 230,232, 234, 236), and in a second mounting position in which the first cooling stage is connected to the low-temperature cooling circuit connection ports via the first cooling stage connection ports (43; 222, 224, 226, 228) and the second cooling stage is connected to the high-temperature cooling circuit connection ports via the second cooling stage connection ports (61; 230,232, 234, 236). a high-temperature cooling circuit piping (44, 46, 48) including high-temperature cooling circuit connection ports; a low-temperature cooling circuit piping (64, 66) including low-temperature cooling circuit connection ports; and a two-stage charge air cooler unit (50; 504, 506) including a first cooling stage with first cooling stage connection ports (43; 222, 224, 226, 228) and a second cooling stage with second cooling stage connection ports (61; 230, 232, 234, 236), the first cooling stage providing a first heat transfer performance, and the second cooling stage providing a second heat transfer performance different from the first heat transfer performance, wherein the first cooling stage connection ports (43; 222, 224, 226, 228) and the second cooling stage connection ports (61; 230,232, 234, 236) have the same geometry and are symmetric to each other with respect to a plane perpendicular to a flow direction of charge air, and wherein the two-stage charge air cooler unit is configured to be mounted in the cooling system in a first mounting position, in which the first cooling stage is connected to the high-temperature cooling circuit connection ports via the first cooling stage connection ports (43; 222, 224, 226, 228) and the second cooling stage is connected to the low-temperature cooling circuit connection ports via the second cooling stage connection ports (61; 230,232, 234, 236), and in a second mounting position in which the first cooling stage is connected to the low-temperature cooling circuit connection ports via the first cooling stage connection ports (43; 222, 224, 226, 228) and the second cooling stage is connected to the high-temperature cooling circuit connection ports via the second cooling stage connection ports (61; 230,232, 234, 236).