It is a oil/water exchange system built by C&R Racing Radiators out of Indy (317-293-4100)which was installed in 2009 with the 408 upgrade. We were getting higher than expected oil temps with the new engine and the exchanger totally eliminated the problems. Oil runs constant with water temp no matter how hard I push it, although I do kick on the 3rd radiator fan on the hot Atlanta days in traffic. You do need to tighten the fittings every once and awhile, but other than that drama free.