Valvoline has previously taken a deep dive into engine coolants, covering their significance and the role these specialized fluids play in vehicle maintenance.
If questions remain about the various coolant types and how to make the best selection, there is no need to worry. Valvoline is here to help. This comprehensive guide walks you through everything you need to know about selecting the correct coolant for your vehicle.
Let's begin by addressing some of the most frequently asked questions surrounding car coolants.
A coolant is a fluid designed to safeguard your engine under extreme conditions — whether scorching heat or below-freezing cold. Its key components include:
1. The glycol base — accounting for 90% to 95% of the coolant concentrate. This base is further divided into two varieties:
Ethylene glycol — prevents the engine fluid from freezing at sub-zero temperatures and from evaporating under intense heat. A notable drawback of ethylene glycol is its tendency to oxidize and cause engine damage, which is why an advanced additive package is necessary to enhance its protective properties.
Propylene glycol — an alternative to ethylene glycol. Its higher viscosity contributes to a better heat transfer rate.
2. Additives — comprising roughly 5% of the coolant concentrate. Corrosion inhibitors are central to coolant technology, as they reduce oxidation and lower the risk of engine rust. The additives used differ across regions and formulations. In Asia, for instance, carboxylates and phosphates serve as the primary anti-corrosion agents, while European formulations typically rely on a blend of silicates and carboxylates.
3. Water — constituting up to 5% of the undiluted coolant concentrate.
Engine coolants deliver a range of important benefits to your vehicle.
Chief among these is preventing engine overheating in warm weather conditions.
Coolants also incorporate antifreeze additives that keep the cooling system from freezing in sub-zero environments. Advanced coolant formulations and blends can maintain engine protection even at the most extreme temperatures, as outlined further below.
Perhaps most critically, coolants shield your engine against corrosion through additives such as phosphates, silicates, and carboxylates, all of which contribute to extending engine longevity.
You may have wondered which coolant type is best suited for your specific vehicle. Unfortunately, there is no one-size-fits-all answer.
Various engine coolant types are meticulously engineered and evaluated for particular vehicle categories. These include Inorganic Additive Technology (IAT), Organic Acid Technology (OAT), Hybrid Organic Acid Technology (HOAT), Phosphate-free HOAT, Phosphated HOAT (P-HOAT), and Silicated HOAT (Si-HOAT).
It is essential to use the coolant fluid your vehicle's manufacturer recommends. The information below will guide you toward the correct coolant choice for your car.
IAT coolants are formulated using ethylene glycol with silicates and phosphates incorporated to provide corrosion protection.
This coolant type is found in older vehicles, typically those manufactured in the U.S. prior to the late 1990s.
Being an older formula, IAT is not as effective as some of the more recent coolant solutions available today.
For owners of older vehicles requiring IAT coolants, the fluid should be flushed and replaced approximately every two years, or at around 72,000 km.
Organic acid technology coolants are formulated with mono ethylene glycol (MEG) and are suited for GM, Saab, and VW vehicles.
In contrast to IAT, OAT coolants are designed for newer car models, generally those produced from the 2000s onward. Organic acids are used in these fluids to guard against engine corrosion, and additional protective additives are also included.
Thanks to their advanced formulation, OAT coolants require replacement only every five years or 240,000 km.
Valvoline's HD Nitrite-Free coolant is one of many advanced OAT-based products in our lineup. Engineered to deliver maximum protection across all metal types, it features advanced corrosion inhibitors and an extended service life.
Hybrid organic acid technology represents the third major category of engine coolants. The HOAT formulation merges the OAT and IAT approaches, drawing on both silicates and organic acids to defend the engine against corrosion.
As with many other coolant categories, HOATs are available in multiple colors. When selecting the right HOAT product, it is therefore better to focus on the brand name and product specifications rather than the color of the fluid.
HOAT coolants are designed for use in Ford, Chrysler, and European vehicle brands, and should be replaced every five years or 240,000 km.
Phosphate-free HOAT uses ethylene glycol as its base and incorporates both organic and inorganic corrosion inhibitors for engine protection. This is a low-silicate, NAP-free formula that is completely free of phosphates, including nitrite, nitrate, and borate.
A wide range of brands benefit from this formulation, including BMW, Volvo, Tesla, Mini, Audi, Jaguar, Porsche, Rolls-Royce, Saab, and Volkswagen.
Among the most trusted phosphate-free HOAT coolants available is the Valvoline OEM Advanced 48 Coolant — a low-silicate, low pH, phosphate-free product suitable for all engine types. It is formulated to prevent corrosion across a broad spectrum of cooling system metals, including aluminum. For passenger cars, the Valvoline OEM Advanced 48 Coolant offers a service life of up to five years or 240,000 km.
This coolant category relies on phosphates and organic acids working together to guard the engine's components against corrosion.
P-HOAT coolants are particularly well suited to vehicles manufactured in Asia, where heat transfer challenges are more common. Compatible brands include KIA, Toyota, Nissan, Hyundai, and Honda. The formulation uses carboxylates and phosphates to effectively reduce corrosive activity within the engine.
For passenger cars, Phosphated HOATs deliver a service life of five years or 240,000 km.
Silicated HOATs combine silicates with organic acids to limit corrosive action inside the engine. This formula is free from nitrites, nitrates, phosphates, borates, amines, and imidazole, placing its emphasis on organic silicate technology.
Protection extends to five years or 240,000 km for passenger cars. Compatible vehicle brands include Mercedes-Benz, Audi, VW, Porsche, Lamborghini, and Bentley.
Valvoline offers an extensive portfolio of high-performance Si-HOAT coolants. Our newest patented Si-OAT formulations are HT-12 Pink and HT-12 Green. These cutting-edge coolant products feature advanced inhibitor packages and are entirely free of nitrites, phosphates, borates, and amines. As an added convenience, they can be mixed directly with tap water.
Now that the different coolant categories have been covered, it is time to identify the right one for your car. The selection process depends on several variables, including the vehicle's type, age, and country of manufacture — all of which serve as your starting point.
Choosing a coolant without prior research, however, can lead to reduced performance or even engine failure. The following steps will help you make the right call.
Color-coding was once a reliable guide in coolant selection. Colors were used to signal different product properties, intended applications, and vehicle compatibility.
This is no longer the case. Coolant colors can vary between manufacturers, and the same color may appear across entirely different products. IAT coolants used in older vehicles, for example, are typically green — yet Valvoline's most advanced Si-OAT formula, HT-12, which is intended for newer vehicles, is also green.
Furthermore, it is worth noting that products within the same coolant category can come in different colors, as seen with our HT-12 Pink and HT-12 Green formulations.
Always bear in mind that vehicle manufacturers have varying requirements, and different models from the same brand may call for different coolant technologies.
Your original equipment manufacturer's guidelines contain clear and specific information about your engine's requirements, including which coolant type is appropriate for your vehicle. If a physical copy of the manual is unavailable, the information can typically be found on the manufacturer's website.
Once you have selected the right Valvoline coolant for your car, understanding how to use it properly is the next step. Here are some straightforward, proven guidelines to follow.
Before changing your vehicle's coolant, check the product label to determine whether the formula requires dilution with water.
Coolants come in two forms: concentrates and ready-to-use formulas.
Ready-to-use coolants are the simpler option, as they come pre-mixed. Concentrates, by contrast, must be combined with demineralized water, with the mixing ratio determined by your local climate conditions.
Consider the Valvoline OEM Advanced 48 Coolant as an example. In its ready-to-use form, it provides protection down to -36°C. When using the concentrate version, it must be diluted with demineralized water — a 40% concentrate mixture protects down to -24°C, while a 50% concentration is required for temperatures below -36°C.
Making the coolant mixture either too diluted or too concentrated can negatively affect cooling system performance. It is important to note that these ratios differ based on coolant temperature and type.
Coolants are effective for a defined service period, during which they protect the engine from deposits, corrosion, and foaming. Irregular or delayed coolant replacement can compromise engine health in several ways, as the cooling system becomes vulnerable to damage when the fluid deteriorates.
The service life of a coolant is measured in years, operating hours, or distance traveled.
As previously noted, older vehicles running on IAT coolants require a fluid change every two years or every 24,000 miles.
Newer formulations offer a longer service life, generally ranging from three to five years. The Valvoline OEM Advanced 48 Coolant and Antifreeze, a hybrid technology product, for instance, delivers a service life of up to five years or 250,000 km.
Insufficient coolant levels can cause the engine to overheat, making it essential to check the coolant regularly.
To do this, park on a level surface and allow the engine to cool completely before opening the hood. Locate the coolant reservoir — most modern vehicles are equipped with a small plastic tank for this purpose, typically marked with a scale indicating maximum and minimum fill levels.
Pay attention to the coolant's appearance as well. A colorless, murky, dark, or rust-tinted fluid is a clear sign of contamination. In such cases, consult a qualified mechanic to inspect the engine and address the issue.
Be aware that coolants contain hazardous chemicals and should always be handled with appropriate care.
If the wrong coolant has been added to the system, it should be removed immediately. Combine a coolant flush solution with distilled water and circulate it through the cooling system. Turn up the heat to ensure the flush passes through the heater core as well. Drain and discard the flush solution, then refill the system with the correct coolant.
With the wide variety of coolant products available today, making the right selection can feel daunting. Vehicle age, manufacturer specifications, and operating temperatures all factor into the decision. Before heading to the store, consult the original manufacturer's guidelines to confirm which coolant type is appropriate for your vehicle.
For premium-quality coolant solutions, Valvoline is the answer. With more than 150 years of expertise in product development and innovation, our extensive range of coolants covers passenger cars, motorcycles, recreational marine vessels, and heavy-duty vehicles.
Browse our full product lineup or reach out to a Valvoline distributor in your region.