DOWFROST™ Heat Transfer Fluid is the only inhibited glycol made with DOW PuraGuard™ Propylene Glycol USP/EP, a pharmaceutical grade of monopropylene glycol with specified purity greater than 99.8%. By contrast, competitor products are often made from recycled or industrial grade glycols, or from glycols derived from bio-renewable sources. These glycols typically do not meet USP specifications as they contain significant amounts of impurities like ethylene glycol or diethylene glycol, which at certain levels affect toxicity. They also may contain certain other impurities, such as dioxolanes which impart strong odors and cause excessive foam. A great way to prolong fluid lifetime and to lower your cost of ownership, is to use DOWFROST heat transfer fluid because it is made with the highest industry purity propylene glycol combined with long lasting, food safe, corrosion inhibitors.