How to choose the right coolant for your car (Professional Guide)

When it comes to engine protection, coolant is essential.  It not only avoids freezing and rust, but it also removes the engine's large quantity of heat and keeps it running smoothly.  However, have you noticed that the difference between different colored coolants on the market is much more than just their appearance?  The key to determining its performance and service life is not the base liquid with the largest proportion, but the "additive package" is important, despite its tiny size. These creative chemical formulations have transformed the coolant from a typical product that must be replenished every two years to a totally organic long-life coolant that can operate continuously for hundreds of thousands of kilometers. The technological advance is buried in this delicate spot.

What Is Engine Coolant?

Modern coolant, often known as antifreeze, can be considered "enhanced water." It is a well-balanced blend of chemical substances, including acids, phosphates, and silicates, with glycol acting as the primary constituent. When combined with water, glycol raises the boiling point and decreases the freezing point, ensuring that the fluid remains stable throughout a wide range of temperatures. The remaining additives have various functions: lubricants keep components like the water pump and thermostat running smoothly, corrosion inhibitors protect the engine's interior surfaces, and dyes—typically orange, green, red, or blue—help identify the coolant type. However, it is important to note that color alone does not necessarily reflect the coolant's composition or compatibility.

What Does Engine Coolant Do?

In an internal combustion engine, energy is generated by burning fuel. Part of that energy powers the vehicle forward, while the rest is converted into heat. Some of this heat exits through the exhaust system, but a significant amount remains trapped within the engine block.

Typical combustion temperatures hover around 2,000°F and can spike to as high as 4,500°F—well above the melting point of aluminum, which is roughly 1,225°F. Without effective cooling, this immense heat could quickly damage engine components.

In fact, a large percentage of engine failures can be traced back to cooling system issues. That’s why engine coolant plays such a vital role—it keeps the engine operating at the optimal temperature, preventing overheating and ensuring reliable performance over time.

How Does Engine Coolant Work?

Car coolant is stored in a reservoir attached to the radiator before it circulates through the engine block and its components.

The coolant works as part of a liquid cooling system, which consists of several key components:

• Water pump (or coolant pump): Circulates coolant throughout the entire system.

• Radiator: Transfers heat away from the coolant.

• Radiator hoses: Connect the different parts of the cooling circuit.

• Fan: Pulls air through the radiator when the vehicle isn’t moving fast enough to provide natural airflow.

• Thermostat: Regulates the coolant’s temperature by controlling its flow.

When the engine is operating, coolant flows continually through the system.  After going through the radiator and cooling, the coolant leaves at the bottom and goes to the water pump.  The pump then pumps it into the engine block and cylinder head, where it absorbs excess heat to keep the engine functioning at its ideal temperature.  The heated coolant then returns to the top of the radiator, where the process is repeated to keep the engine at a safe and efficient temperature.

Engine Coolant Types

Corrosion inhibitors constitute the largest portion of the coolant additives found in engine coolant. The three principal types differ in chemical composition, each designed to provide distinct protective characteristics tailored to various cooling system designs.

Inorganic acid technology coolant (IAT) 

Inorganic Acid Technology coolant represents the conventional formulation long used in older vehicles. Due to the faster depletion of its corrosion-inhibiting additives, it requires more frequent replacement intervals. IAT coolant is most commonly identified by its green or yellow appearance.

Organic acid technology coolant (OAT)

The Organic Acid Technology (OAT) coolant varies from the standard silicate-based IAT coolant.  It has no silicates or phosphates and instead employs organic salts to preserve the cooling system, resulting in a substantially longer service life.  However, OAT coolant is incompatible with systems that use yellow metals like copper or brass, making it unsuitable for older automobiles.  It is best suited for contemporary engines with aluminum components.

 OAT coolants, developed in response to environmental concerns, provide longer service intervals, fewer maintenance costs, and a smaller environmental effect.  They take longer to establish a protective layer, and brief contact with moisture can cause corrosion, making their performance slightly less robust than typical IAT coolants.

Hybrid organic acid technology coolant (HOAT)

The hybrid organic acid technology coolant can be regarded as a combination of OAT and IAT technologies. It is based on organic acids and compounded with a small amount of inorganic corrosion inhibitors such as silicates or phosphates. It takes into account the long life of organic acids and the rapid protection of inorganic acids for a variety of metals. It is more common in some European and American car brands.

What Type Of Coolant Does My Car Need?

Standard first, coolant color is for reference only. This is the simplest section to do incorrectly. The answer is that when choosing coolant, the only solid basis is the original standard or approved model listed in your owner's manual.

Technical standards are essential: most multinational automakers have their own stringent coolant standards.  For example:

• German brands (Volkswagen, Audi, Mercedes-Benz, BMW) often adhere to G12, G12++, G13, G12evo, and other norms, with tight restrictions for silicate content.

• American (GM, Ford): Dex-Cool technology is common, and most solutions contain organic acids, which necessitate long-term efficacy.

• Japanese/Korean manufacturers (Toyota, Honda, Hyundai) primarily employ phosphate-based formulations.

A word of caution concerning color: Coolant color is simply a dye provided by the manufacturer to help spot leaks and avoid inadvertent intake.  This is not a compatibility requirement!  The chemical compositions of green coolants from various manufacturers may range significantly.  Mixing coolants of different standards might cause the additives to react, resulting in precipitation, blocking the water tank, and major issues such as engine cylinder pulling.

What Are The Signs That You Need to Add Coolant?

The state of the coolant is the "barometer" of the health of the engine cooling system.

Health status: clear, bright, no suspended matter, no oil pollution.

Warning signals:

• Cloudy, discolored: Turns rusty or brown, suggesting extensive corrosion of metal parts. 
• The coolant light on car indicates engine coolant low or that the engine is overheating. Stop safely, allow the engine to cool, and check the coolant level before driving.
• Oil stains: If there are oil-like floating items on the liquid surface, it is highly likely that the oil cooler has broken, allowing the oil and coolant to mix. 
• If the coolant becomes thick or lumpy, it means that the additives have failed or that a chemical reaction has happened due to the mixing of incompatible coolants. 
• Abnormal consumption too quickly: It is possible that there is an exterior leak (check the pipeline and water tank) or an interior leak (cylinder gasket damage, displayed as white smoke from the exhaust pipe and engine oil emulsion).  

Emergency handling: If the coolant boils over during a long-distance trip, stop the car immediately and let it idle. Do not open the hot expansion tank cover immediately to avoid being burned by the steam. After the engine has cooled down naturally, check it and call for help.

How Often Should To Change Coolant?

Periodic Inspection:

With the engine in a cold state, inspect the coolant level in the reservoir at regular intervals. The level must remain between the “MAX” and “MIN” markings. Any deficiency should be corrected immediately by replenishing the coolant.

Scheduled Replacement:

Coolant undergoes chemical degradation over time, reducing its buffering capacity and corrosion-inhibition properties. Performing a coolant fluid change at the intervals specified in the vehicle’s service manual—typically every 2–5 years or 40,000–100,000 km—is essential, rather than relying solely on partial top-ups.

System cleaning:

The cooling system should be thoroughly cleaned with a Coolant System Cleaner each time the coolant is changed to remove accumulated impurities.

Keeping the cooling system in top condition not only ensures that the engine always operates within the ideal temperature range but also significantly extends the life of the engine, allowing your car to maintain excellent performance and reliable quality.

What Is The Difference Between Car Coolant And Motorcycle Coolant?

They have the same basic functions (cooling, antifreeze, rust prevention), but there are great differences between motorcycle and automobile engines in specific design and requirements, so the formula of coolant needs to be adjusted in a targeted manner.

Why Is It Not Recommended To Mix Them?

Damage to the wet clutch (the most critical reason)

• Many motorcycles (especially street bikes, ADVs, and touring bikes) share the same lubrication/cooling system for the engine, transmission, and wet clutch (although the clutch and coolant are not directly mixed, they are closely adjacent).

• An additive commonly used in automotive coolant (mainly silicate organic acid technology) can damage the wet clutch friction plate of motorcycles, resulting in clutch slippage, which seriously affects power and driving safety.

• Motorcycle-specific coolants often use safer formulations such as phosphate organic acid technology to avoid this problem.

Different pump protection requirements

• Motorcycle engines typically run at much higher speeds than car engines, and the water pump impeller is smaller and spins faster.

• Motorcycle coolant contains more effective anti-foam additives to prevent the formation of air bubbles, ensuring that the water pump impeller is always surrounded by liquid for effective circulation. If cavitation occurs, it will damage the water pump and reduce cooling efficiency.

The material compatibility is stricter

• Motorcycle engines use a wider variety of aluminum alloys, magnesium alloys, and different welding materials (such as soft solder).

• The special coolant is formulated to better protect these specific materials, prevent electrochemical corrosion, and prevent sediment from blocking narrow waterways.

To save time and money, avoid using automotive coolant on your motorcycle's engine, clutch, and water pump. Purchasing a container of the appropriate motorcycle-specific coolant is a simple investment in safeguarding your bike that may save you from costly repairs down the road.

Conclusion - How to choose the right coolant for your car

Final Tips for Maintaining a Healthy Cooling System.

As modern automobile technology gets more advanced and complicated, the proper selection and use of coolant has become an essential component of intelligent vehicle maintenance.  If you haven't checked the coolant level or are unclear if the product you're using is appropriate, don't wait until the dashboard lights up with an overheating alert to take action.  Problems with the cooling system frequently begin with modest concealed concerns, but they can soon escalate into significant repercussions that necessitate costly repairs.