BlueDEF DEF002 Diesel Exhaust Fluid - 2.5 Gallon Jug (Pack of 2) Mixture of 32.5 percent high purity synthetic urea and 67.5 percent deionized water Helps convert nitrogen oxide into harmless nitrogen gas and water vapor for cleaner emissions Improves fuel economy by up to 5 percent Inject the fluid into your exhaust stream with a specialized dosing module Stable, colorless, odorless, and meets ISO standards 22241 for purity and composition