Refractometer for Testing Engine Coolant and Extended Life Coolant
The proper coolant concentration is important for providing optimal cooling properties, freeze protection, and corrosion protection.
Although engine coolant technology has changed much in the last two decades, it still performs three basic functions:
- In hot weather, it cools the engine.
- In cold weather, it keeps the coolant from freezing.
- In all weather, it provides corrosion protection.
Things are not as easy as they once were. In the old days, there was the standard ethylene glycol engine coolant with IAT corrosion inhibitors. Today, engine coolants are still mostly ethylene glycol, but the corrosion inhibitors’ chemical makeup differs.
There are three main types of engine coolant, all of which you can test with a MISCO refractometer:
Inorganic Additive Technology (IAT)
IAT is the old standard and had a vivid green color. It worked well, but the additives depleted over time and required changing roughly every 24,000 miles. It is seldom used anymore, in favor of new chemical additive packages that extend coolant life.
Organic Acid Technology (OAT)
OAT technology represents a new class of extended life engine coolants. It provides a serviceable life of around 50,000 miles for most vehicles. These coolants, used by General Motors and others, can be orange, yellow, red, or purple and are incompatible with other types of coolants.
Hybrid Organic Acid Technology (HOAT)
HOAT represents another extended life engine coolant chemistry used by Ford, Chrysler, and others. The HOAT coolant, which is yellow or orange, provides extended life from 50,000 to 150,000 miles, depending on the vehicle.
It is essential to top-off the coolant with the like-kind; otherwise, cooling system trouble may result. The owner’s manual for each vehicle will provide guidance on the recommended type of engine coolant. Although each coolant type has representative colors, do not depend on color alone as an indication of the kind, since color can change while in use and through mixing with different colors of the same kind of coolant.