 Diesel vehicle emission controls begin with proper maintenance and fluids, like DEF or diesel exhaust fluid. Featuring a mixture of high purity synthetic urea and deionized water used in SCR or selective catalytic reduction, Blue Deaf Diesel Exhaust Fluid offers a purity guarantee to meet or exceed the strictest OEM standards. And Blue Deaf Platinum features advanced system shield technology, which includes a proprietary formula to tackle deposits built up in the SCR system.