Provides engine and potable water system protection in extreme cold environments. Winterizing your boat for the off-season protects your investment and can prevent costly repairs in the spring. Star Brite WinterSafe -100 degree (-73 degreeC) Marine Antifreeze provides oustanding cold weather and corrosion protection for drinking water systems, sanitation systems and all engines. Non-toxic formula uses pure virgin propylene glycol for effectiveness and quality. Virgin (not recycled) propylene glycol reduces residual smell and tastes so that drinking water systems are not adversely affected by winterization. Includes corrosion inhibitors to prevent damage to metal engine components and seals. Star Brite WinterSafe is alcohol free to reduce evaporation so that antifreeze maintains same concentration and protection throughout the storage season. The intense blue color lets users know when antifreeze has traveled through water lines, sanitation system lines or engine cooling systems and serves as an indicator when flushing systems in the spring. Star Brite WinterSafe is the professional choice for winterizing potable water systems, sanitation systems and engines.