Automotive Coolant - Chrysler Valiant

Automotive coolant, also known as antifreeze, is one of the most critical fluids in any vehicle. Its primary role is to regulate engine temperature, preventing overheating in summer and freezing in winter, ensuring that the engine and the radiator stay operational. In addition to temperature regulation, coolant plays an important part in reducing corrosion, preventing scale buildup, and ensuring the longevity of the engine.

However, not all coolants are created equal. There are several types and grades of automotive coolants, each with distinct properties, benefits, and drawbacks.

What is Automotive Coolant?

Automotive coolant is a liquid mixture that is used to absorb heat from the engine, carry it to the radiator, and release it into the air. Coolant is typically composed of a mixture of water, antifreeze, and additives to enhance its effectiveness in preventing freezing, boiling, and corrosion.

The primary functions of automotive coolant include:

Temperature Regulation: Coolant absorbs excess heat from the engine, preventing it from overheating.
Freezing Protection: It prevents the coolant from freezing in cold weather by lowering its freezing point.
Corrosion Prevention: Coolant contains additives that prevent rust and corrosion in the engine and radiator components.
Lubrication: It helps to lubricate the water pump and other moving parts in the cooling system.

Basic Composition of Coolant:

Water: The primary component of coolant, responsible for absorbing and transferring heat.
Antifreeze (Ethylene Glycol or Propylene Glycol): A chemical compound that lowers the freezing point and raises the boiling point of the coolant mixture.
Additives: Antioxidants, anti-foam agents, and corrosion inhibitors that ensure the cooling system’s longevity and efficiency.

Now, let’s dive deeper into the types and grades of automotive coolant.

Types of Automotive Coolant

Automotive coolants are categorized based on the chemicals used in their formulation, and the two main groups are inorganic additive technology (IAT), organic acid technology (OAT), and hybrid organic acid technology (HOAT). These categories differ in terms of the type of antifreeze used, the additives, and the coolant’s intended lifespan.

1. Inorganic Additive Technology (IAT) Coolants

IAT coolants are the traditional, most commonly used coolants, and they have been in use for decades. This type of coolant is typically based on ethylene glycol (EG) and uses silicate-based inhibitors to prevent corrosion.

Pros of IAT Coolants:

Well-established: IAT coolants have been around for a long time, and their performance is well-understood.
Wide Availability: As the most common coolant type, IAT coolants are easy to find at most automotive stores.
Affordable: Generally, IAT coolants are less expensive than newer coolant technologies, making them a cost-effective option for older vehicles.

Cons of IAT Coolants:

Shorter Lifespan: IAT coolants tend to have a shorter service life compared to more modern coolant formulations. Typically, IAT coolants need to be replaced every 2 years or 30,000 miles.
Corrosion and Scaling: The silicate-based inhibitors can contribute to scale buildup, which may damage components like the radiator and water pump over time.
Less Effective in Modern Engines: Newer engine materials and designs may require more advanced coolant technologies to ensure better protection.

Best for: Older vehicles or cars that require a specific IAT coolant, especially those manufactured before the 1990s.

2. Organic Acid Technology (OAT) Coolants

OAT coolants use organic acids instead of inorganic silicates to prevent corrosion. These coolants are formulated without silicates, phosphates, or borates, relying instead on organic acid-based inhibitors.

Pros of OAT Coolants:

Longer Lifespan: OAT coolants typically last between 5 and 7 years or up to 150,000 miles, making them ideal for newer vehicles. This long-lasting formula reduces the frequency of coolant changes.
Corrosion Inhibition: The organic acids in OAT coolants are specifically designed to prevent corrosion, making them ideal for aluminum engines, which are more susceptible to corrosion.
Environmentally Friendly: OAT coolants generally contain fewer toxic chemicals compared to IAT coolants, making them less harmful to the environment.

Cons of OAT Coolants:

Higher Cost: OAT coolants are typically more expensive than IAT coolants, both in terms of purchase price and the potential cost of replacing it less frequently.
Not Compatible with Older Vehicles: OAT coolants should not be mixed with IAT coolants because the chemical composition may cause reactions that decrease effectiveness. For this reason, using the wrong coolant could damage the radiator or engine.
Requires Proper Maintenance: Although OAT coolants last longer, they can break down over time, particularly if the system becomes contaminated. Proper maintenance, including flushing the system at the manufacturer-recommended intervals, is crucial.

Best for: Newer vehicles (post-1996) with aluminum engines, as well as for long-term reliability and reduced maintenance frequency.

3. Hybrid Organic Acid Technology (HOAT) Coolants

HOAT coolants combine the best features of IAT and OAT coolants. These coolants use both organic acids and some inorganic additives (like silicates) to provide enhanced protection and longevity. HOAT coolants are designed to meet the needs of a wide range of vehicles.

Pros of HOAT Coolants:

Balanced Performance: HOAT coolants offer the benefits of both silicates and organic acids. They provide superior corrosion protection while also offering a longer service life, often 5 years or 150,000 miles.
Wide Compatibility: HOAT coolants can be used in a broad range of vehicles, including newer and older models, without the issues of mixing incompatible coolants.
High Heat Tolerance: The combination of organic and inorganic inhibitors provides excellent heat transfer and protection against high temperatures.

Cons of HOAT Coolants:

More Expensive: HOAT coolants tend to cost more than IAT coolants, although they are often less expensive than OAT coolants.
Not Always Eco-friendly: While more environmentally friendly than IAT coolants, HOAT coolants may still contain some toxic additives that are not ideal for the environment.

Best for: Vehicles with modern engines, especially those made by manufacturers like Ford, Chrysler, and certain European brands, which recommend HOAT coolants.

4. Propylene Glycol-based Coolants

Propylene glycol-based coolants are an alternative to ethylene glycol coolants. While ethylene glycol is the most common type of antifreeze, propylene glycol is seen as a safer, more environmentally friendly alternative.

Pros of Propylene Glycol-based Coolants:

Non-toxic: Propylene glycol is less toxic than ethylene glycol, which can be harmful or fatal if ingested. This makes propylene glycol coolants a safer option for pets and wildlife.
Environmentally Friendly: Because of its lower toxicity, propylene glycol is considered more environmentally friendly, making it a better choice in situations where coolant may be spilled or improperly disposed of.
Corrosion Inhibition: It offers corrosion protection similar to ethylene glycol-based coolants and can be formulated to meet OAT, HOAT, or IAT standards.

Cons of Propylene Glycol-based Coolants:

Higher Cost: Propylene glycol-based coolants are typically more expensive than traditional ethylene glycol coolants.
Lower Heat Transfer Efficiency: Propylene glycol has a slightly lower heat capacity and performance compared to ethylene glycol, meaning it may not be as effective in extreme temperature conditions.
Limited Availability: While widely used in some markets, propylene glycol-based coolants are less common than ethylene glycol coolants, making them harder to find in certain areas.

Best for: Drivers who are particularly concerned about the environmental impact or pet safety and are willing to pay a bit more for the peace of mind that comes with using a non-toxic coolant.

5. Silicate-Free Coolants

Silicate-free coolants are a more recent innovation aimed at improving the performance and longevity of your car’s cooling system. These coolants avoid the use of silicates, which are commonly found in traditional IAT coolants, and use alternative corrosion inhibitors instead.

Pros of Silicate-Free Coolants:

Improved Cooling System Health: Silicate-free coolants reduce the risk of silicate deposits clogging the radiator, which can happen with traditional IAT coolants.
Better Compatibility: These coolants are compatible with both older and newer vehicles, making them a versatile option for various types of engines.
Longer Service Life: Like OAT and HOAT coolants, silicate-free coolants tend to have a longer lifespan and are designed for extended use (5 years or 150,000 miles).

Cons of Silicate-Free Coolants:

Higher Price: These coolants are often more expensive than conventional IAT coolants.
Limited Availability: Although becoming more common, silicate-free coolants are still not as widely available as traditional IAT or HOAT coolants.

Best for: Drivers with modern engines who want a coolant that offers high protection, less maintenance, and improved system longevity without silicate buildup.

Choosing the Right Coolant for Your Vehicle

When selecting coolant for your vehicle, it is crucial to consider the following factors:

Manufacturer Recommendations: Always check your vehicle’s owner manual for the recommended type of coolant. Using the wrong type of coolant could cause damage to your engine or void the vehicle’s warranty.
Climate: The climate in which you drive should influence your choice of coolant. In colder climates, ensure that the coolant has sufficient antifreeze properties to prevent freezing. In hot climates, opt for a coolant that can withstand high temperatures and prevent overheating.
Vehicle Age and Engine Type: Older vehicles may require IAT coolants, while newer vehicles often need OAT or HOAT coolants. Vehicles with aluminum engines may benefit from OAT or HOAT coolants, which offer better corrosion protection.
Environmental Concerns: If you are concerned about the environmental impact, consider using propylene glycol-based or silicate-free coolants, which are safer for wildlife and easier to dispose of.
Cost and Longevity: Consider how much you are willing to spend on coolant. If you want a longer-lasting coolant that reduces the need for frequent maintenance, OAT, HOAT, or silicate-free coolants may be the best choice.

Conclusion

Automotive coolants come in various types and grades, each designed to serve specific purposes and address particular needs. Understanding the differences between IAT, OAT, HOAT, propylene glycol-based, and silicate-free coolants can help you make an informed decision that ensures your engine operates efficiently and stays protected for the long haul.

Each coolant type has its advantages and drawbacks. IAT coolants are inexpensive and effective for older vehicles, while OAT and HOAT coolants offer longer service lives and better corrosion protection for modern engines. Propylene glycol-based coolants provide a safer, more environmentally friendly alternative but at a higher cost.