American Petroleum Institute

For landscapers and others involved in outdoor work and snow removal, there is always plenty of annual winter preparation. But one thing that may be overlooked is the proper management of Diesel Exhaust Fluid (DEF) used in many diesel-powered trucks. Handling and storing DEF can be challenging in winter. Made from a mixture of technically pure urea and purified water, DEF freezes at 11 degrees F and needs to be properly maintained and dispensed to preserve its quality. Like water, DEF will expand up to 7% when frozen and can damage a storage tank if it is full or nearly full when freezing. If you have a tank you think may freeze, it’s a good idea to keep it less than full. If DEF freezes in the vehicle, do not put any additives in the tank to help it melt. DEF needs to remain pure for it to work correctly. The vehicle will start without a problem and the DEF tank has a heating element that can quickly thaw the DEF. Don’t worry; on-spec DEF is specifically formulated to allow the fluid to thaw at the proper concentration to keep your vehicle operating smoothly. In addition to freezing temperatures, there are other considerations when purchasing, storing, and handling DEF. Drivers accustomed to purchasing DEF in containers should always look at the expiration date on the bottle—and be sure to use it before this date—since DEF has a limited shelf life. If a date is not present, ask for the most ...