Design Engineering Heater Hotter (also known as Quick Heat in some markets) is an additive which allows your vehicles engine to warm up faster. Because your engine warms up faster so does your heater which is great for those frosty winter mornings.Heaters works up to 50% faster, ideal for defrosting on winter morningsCompatible with all coolants and anti freezesEasy to use, simply add to your coolant systemDesign Engineering Heater Hotter works by reducing the surface tension in the coolant and stops tiny bubbles forming which insulate the engine from the coolant. Without these bubbles (cavitation) the coolant is able to transfer heat from the engine much more efficiently.473ml Bottle