Anti-freeze types

There are only 3 main types of anti-freeze:

Green Anti-freeze:

These are the traditional type of anti-freeze most commonly used in North America. Their silicate and phosphate composition provides protection for aluminium and bare iron surfaces. They need to be changed every 30,000 miles or once every two to three years.

OAT (Organic Acid Technology) anti-freeze:

These contain ingredients such as 2-EHA, sebacate and other various organic acids. Unlike green anti-freezes, they generally do not contain silicates or phosphates. Usually, OAT-based coolants will be dyed a different colour to green anti-freeze. They must be changed once every five years or 150,000 miles.

HOAT** (Hybrid OAT)** anti-freeze:

These use organic acids but not 2-EHA and usually include silicates to provide protection for aluminium surfaces. HOAT anti-freezes are used by many European car manufacturers, although they are also used by American companies such as Chrysler and Ford. A HOAT coolant will need to be changed every five years or 150,000 miles. In recent years, anti-freeze manufacturers have been creating universal coolants that can be used with all vehicle types. These extended-life coolants only differ in colour. Some may be orange while others may be dyed blue or purple.