Serious problems related to quench oil contamination have always affected the heat treat industry. These problems have led to shortened oil life, variations in the quench curve, loss of production time, unplanned maintenance, sludge accumulation, surface deposits, and massive amounts of rework costs associated with additional part cleaning. This paper will detail the causes for contamination, including; carbon deposits, oxidation of the oil that result in unwanted by-products, ingress of dirt from parts and external sources, and water ingress. We also discuss a way to eliminate the extensive downtime associated with excessive sludge, and cleaning of reservoirs and equipment. The paper will give visual representations of the effects of quenching in dirty oil vs. quenching with clean oil. Additionally, we will look at several case studies that show the relationship of clean oil to clean parts and proper quenching properties. The paper will also detail various methods of particulate and water removal and how effective they are with the quench oil application. This session would be important for the attendees that are utilizing quench oils and are looking to extend their oil life, quality of their parts, and reducing overall costs associated with the process.