Prevents Crystallization – Reduces harmful DEF crystal buildup in pumps, injectors, and SCR systems. Improves Stability – Extends DEF shelf life by protecting against degradation. Maintains System Efficiency – Helps ensure proper dosing and smoother operation. Protects Investment – Reduces downtime, repairs, and costly replacements. Compatible with all DEF fluids and systems, Easy-to-use 8oz single-dose bottle Doc’s DEFGUARD is a premium Diesel Exhaust Fluid (DEF) additive formulated to protect, stabilize, and extend the life of DEF in your system. Designed for modern diesel engines, it ensures peak performance and system reliability.