Choosing the right brand of radiator fluid is a more important decision than choosing what kind of oil or which kind of gas to put in your engine. Radiator fluid, however, is usually the last engine fluid you think of. Although there is a vast range of radiator fluid brands on the market, you can divide them into three basic categories: yellow, green and orange. Each of these protects your engine in a different way so it’s important to buy the right radiator fluid for your vehicle.
Yellow radiator fluid is considered the universal radiator fluid, allowing you to top up any radiator fluid in a pinch. You can combine yellow radiator fluid with either green or orange fluids, so long as you get a complete system flush as soon as possible. On its own, yellow anti-freeze can be used in either diesel or gasoline engines.
Most people recognize engine coolant as being green. Green radiator fluids contain silicates that help it circulate better in older model cars. The rust inhibitors in green anti-freeze are designed for the copper-and-brass radiators found in most Japanese cars and older American and European built cars.
Radiator fluid brands such as Havoline Dex-Cool and Prestone Extended Life are either red or orange in color. These anti-freezes are the most recent to be offered on the market and contain the organic acids, a new rust inhibitor. These radiator fluids are designed for newer cars that have an aluminum radiator and should not be used in cars with a copper-and-brass radiator.