For Heavy Duty Industrial Hydraulic System Cooling. 33.93" W x 25.7" H. Hydraulic oil coolers, also called heat exchangers, use air or water to cool fluid in hydraulic systems. They pass oil through a coil or core to cool the oil before it enters the system. Heated oil causes excess wear on seals, surfaces, and other components, which can cause particulate buildup, damage components, and shorten the system's life span. Water oil coolers are compact and can be used in high-pressure applications such as those found in oil refineries and chemical processing plants. Air oil coolers ...