Antifreeze coolant is one of the most vital fluids in your car\'s operation, since it protects the engine from corrosion, from boiling or freezing temperatures, and helps transfer heat from the engine to the radiator. While water could potentially serve the purpose of heat transferring, most coolants only contain 2-4 percent water, which is subject to freezing and boiling. The main ingredient of coolant is glycol; usually, ethylene glycol, and the rest are additives which protect your car\'s inner workings against corrosion, rust, and pitting caused by air bubbles imploding in the cooling system.The D/ISHA4 is a concentrated all year round protection anti-freezing liquid type with low freezing point, designed for all engine types including full-aluminium ones. This D/ISHA4 S Hook 4.5 litre blue liquid protects the cooling systems against damage by freeze to -36 degrees Celsius and corrosion. Also the S Hook D/ISHA4 will keep you car cooler in summer months, so getting all year round protection for a great low price. Antifreeze blue is the optimum composition of top grade ethylene glycol, combined with treated, de-mineralized water and high-performance additive package that prevents formation of rust and scum. The S Hook antifreeze will protect and help to prolong the pump bearing service life, prevent water pump seizure and other rubber parts of the cooling system from dry out and cracking. D/ISHA4 Antifreeze blue is notable for its high heat-transfer capacity, low viscosity, excellent detergency. 4.5 LitrePasses BS6580 1992.