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Guide to Choosing the Right Coolant for Your Truck

Australia has one of the most competitive commercial vehicle industries in the world. The country’s vast landmass requires trucks to cover long distances between cities and ports. They also experience extreme weather conditions all year round. The optimal performance of the truck depends on the regular maintenance of all its components.


A truck’s cooling system has a significant role in its overall performance. Poor cooling system maintenance is responsible for almost 50% of all truck engine problems. This article outlines the main factors to consider when choosing a coolant fluid for your truck. Read on if you would like to know more about the types of coolant available for heavy commercial vehicles.


Type of Coolants for Heavy-Duty Vehicles

The main function of engine coolant fluid is to regulate the temperature of a truck’s engine during operation. In a hot climate, the coolant prevents the engine from overheating. Yet in cold weather, the coolant’s antifreeze components prevent the engine’s fluids from freezing. Coolants also minimize corrosion in the delicate parts of the engine.

Engine coolant fluids are available in a wide variety of colours. Yet, there are only three main types of coolants used in commercial vehicles. These are


  • Inorganic Acid Technology, IAT
  • Organic Acid Technology, OAT
  • Hybrid Organic Acid Technology, HOAT


1.      Inorganic Acid Technology, IAT Coolant

Conventional coolants for commercial vehicles are based on Inorganic Acid Technology. IAT coolants are suitable for vehicles manufactured before the year 2000. To distinguish IAT from other engine fluids, manufacturers add a bright green or purple tint to it.

IAT contains additives such as silicates and phosphates to protect the engine’s components from corrosion. It is especially effective against wet sleeve liner corrosion. This helps to extend the life of the steel, copper and aluminium parts of the engine.

Yet, the corrosion inhibitors have a fast depletion rate. As such, the IAT coolants need to be flushed out and replaced every 2 years.  For long-distance trucks, the fluid should be replaced after every 48,000 km.


2.      Organic Acid Technology, OAT Coolants

OAT coolants last longer than the conventional IAT coolants. Instead of silicates and phosphate additives, the OAT coolants contain carboxylate acid corrosion inhibitors. These inhibitors enable OAT coolants to last up to 5 years or 240,000 km before needing replacement.

OAT coolants are mostly red or orange, yet some manufacturers give them a dark green tint. They are best suited for vehicles manufactured after the year 2000.


3.      Hybrid Organic Acid Technology, HOAT Coolants

HOAT coolants optimize the benefits of Organic and Inorganic Acid Technology. They contain silicate additives as well as the OAT long-life technology. This increases the coolant’s corrosion resistance and longevity.

As such, they have the same lifespan as the OAT coolants. Technicians only need to flush and replace HOAT coolants after 5 years of 240,000 km. HOAT coolants are typically yellow, orange or red.

It is important to keep in mind which type of coolant your truck uses. This is because the three different types of coolant should not be mixed. Most manufacturers specify the recommended type of coolant each vehicle models. Yet, the coolant’s distinct colours and tints make them easier to distinguish from each other.

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