• IAT – Inorganic Additive Technology
For decades, this distinctive green-colored coolant protected cooling systems, but it is rarely used as factory fill in modern cars. One reason is the fast depletion rate of its additives, which means it has to be changed more frequently, usually every two years or 24,000 miles.
• OAT – Organic Acid Technology
Commonly required for vehicles manufactured by General Motors, and some other automakers, OAT coolants are not compatible with other types. Usually orange, yellow, red or purple, OAT coolants are typically changed every five years or 50,000 miles.
• HOAT – Hybrid Organic Acid Technology
Providing the benefits of both IAT and OAT coolants, HOAT coolants are primarily orange and yellow and are common in Chrysler and Ford vehicles. OAT coolants are typically changed every five years or 50,000 miles, although some automakers specify intervals as long as 10 years or 150,000 miles.
• Hybrid and Electric Vehicle Cooling Systems
Most hybrid and electric vehicles have a separate cooling system for the battery pack. Only coolants that meet the automakers’ specifications should be used in these systems.
1. Coolant type cannot be accurately identified by color. Both OAT and HOAT are often orange or yellow, so they can be easily misidentified.
2. Automakers don’t adopt new coolants on a simple schedule. It’s entirely possible for two vehicles from the same manufacturer to use two completely different coolant types.
3. Just because a vehicle had one type of coolant when it left the factory doesn’t mean a different type of coolant wasn’t installed at some point in the life of the vehicle. When changing back to the factory recommended coolant, a complete cooling system flush should be performed first.