High performance quench oil must have oxidation resistance or low sludge formation, be non-staining, an elevated flash point and have acceptable heat transfer characteristics. Contamination of quench oils is a very serious problem in most cases. Oxidation Deposits (Resins) in combination with the frequently very high temperature of the quench oil, the above contaminants will accelerate the decomposition of the oil and resin-like deposits will form. This will, in turn, severely reduce the efficiency of the oil coolers, the aqua-alarm system and the quenching process in general.