Radiator coolant is an essential fluid for your vehicle’s performance. This blog article is your go-to source of information on coolants, specifically with regard to specifications, colours, compatibility/miscibility and more.

1. Coolant As An Essential Fluid For Your Vehicle

How does the coolant work in your vehicle?

Radiator coolant is one of the most indispensable fluids for your vehicle. Think of how your body uses sweat to cool itself on a hot day: it transfers excess heat to water and then into the outside air. Your engine operates through a similar process. A water pump pushes the radiator coolant throughout your engine. The water in this fluid cools the engine’s components as it passes, picking up heat. This hot fluid then returns to the radiator. In the radiator, the passing outside air extracts some of the fluid’s heat. The coolant is pumped back into the engine for another cycle.

What would happen to an engine without radiator coolant?

Things would get grim fast. After all, your car is powered by burning fuel, creating very high temperatures very quickly. Without a cooling system, it doesn’t take long for your engine to overheat fast and hence break.

Does your Electric Vehicle also need a cooling fluid?

Yes, electric vehicles require cooling fluids to maintain optimal operating temperatures. Efficient temperature control is crucial for the performance and longevity of the batteries and other components. Specialised coolants for EVs prevent overheating, protect against frost, and prevent deposits from forming. These coolants are designed to work with the materials used in EV systems, ensuring compatibility with elastomers and hoses used by most European manufacturers.

2. Difference Between Coolant And Antifreeze

What is the difference between antifreeze and coolant?

Antifreeze is a concentrated form of coolant, so before its use, it needs to be diluted. Coolants are ready-to-use fluids, consisting of antifreeze mixed with demineralized water.

The ready-to-use mix is a quite common blend to safeguard the performance properties of the antifreeze. Different ratios are possible depending on local climate, but ultimately checking what was initially used by the manufacturer of your car is the best option.

Can I also dilute antifreeze with tap water?

You can use tap water in an emergency, but it is not recommended. Tap water usually has a certain hardness due to the presence of calcium carbonate and magnesium. If the coolant is not compatible with the water used, precipitates can form and, in the worst cases, it can lead to blocking of the system or to water pump failure!

Can I use water instead of a coolant?

Water alone would eventually boil off, causing the engine to rapidly overheat. On the other end, a water-only system would also be vulnerable to freezing in the winter, causing the cooling system to malfunction or break due to ice formation.

What’s the benefit of buying a coolant versus buying antifreeze and mixing it with distilled or deionized water?

Antifreeze being a concentrated form of coolant, cannot be put straight into the vehicle, it must be diluted. Finding the right percentage is very important, because otherwise it will not provide sufficient protection, and in certain cases, could create cavitation problems to the engine.

Coolant, on the other hand, is a ready-to-use blend of antifreeze and demineralized water. Using coolant instead of antifreeze offers convenience, precision, and consistent performance to reach the optimal required temperature and cooling system performance.

3. The Importance Of The Quality Of A Coolant

Why is the quality of the coolant I use so important?

Cooling system failures account for around 20% of engine failures. And 60% of water pump failures are due to incorrect or low-quality coolant! Just 0.6mm of surface deposits within a vehicle’s cooling system can cut heat dissipation by up to 40%. With modern engines designed to be smaller and lighter with higher specific power output, they often have higher operating temperatures. If your cooling system is not working effectively, this can lead to overheating and, potentially, permanent catastrophic damage to the engine.

Can the wrong coolant damage my engine?

Yes, there are several reasons why using the wrong coolant can be harmful to both your cooling system and the engine.

Low-quality coolant: Choosing low-quality coolant or antifreeze risks exposing your cooling system to rust and scale build-up, leading to reduced efficiency and potential overheating.

Incorrect coolant: If you use the wrong coolant, you risk combining two fluids that are causing loss of the protection capacity. This will not effectively cool your engine and you will need to flush the system before something fails.

Choosing the appropriate type of coolant or antifreeze from a reputable manufacturer like Wolf Lubricants will help regulate engine temperatures and improve the longevity of both the engine and the cooling system.

4. Colours & Specifications

Why are there different colours of coolants and antifreeze?

Colours are important only for safety reasons. A coolant without additional colours is water-white and that could be dangerous if people are not being careful. Different colours are added to prevent the misuse of the fluid, and to simplify the choice, the several blenders tend to use the same colour as the OEM manufacturer.

Does it matter which coolant specification (G12+ for example) you use?

What is more important than the coolant colour, which has no impact on the performance of the fluid, is the coolant specification (G12+, for example) which determines its composition and suitability for a vehicle.

If you are using the manufacturer’s recommended coolant specification but it is different than the colour already in your cooling system, it is safe to mix them. However, if you are unsure about the origin or specification of the old fluid, it is strongly recommended to flush the cooling system before applying the new coolant.

What is the composition of each coolant?

The typical composition of the coolant is water and glycol (generally ~50% each for optimal protection from freezing), plus a small percentage of additives. However small this percentage, it serves an important function for engine protection. These additives are a balanced portion of corrosion inhibitors, stabilizers, dispersants, antifoam and dye.

Over the years the technology evolved from a rather traditional technology, among which the most significant are silicates and phosphates, to the OAT, which stands for Organic Acid Technology. This OAT maintains a higher long-term cooling efficiency and offers additional advantages like improved stability, water pump life extension, and excellent protection against cavitation.

The latest innovative technology in coolants is the G12 EVO specifications; this is a high-performing coolant based on ethylene glycol with state-of-the-art PSi-OAT corrosion protection for high-performing engines. With the PSi-OAT technology, organic acids work together with traditional inhibitors for the best possible protection.

EVO LongLife

The EVO LL uses environmentally friendly additives with low toxicity and high biodegradability. Wolf Lubricants uses mono-ethylene glycols with state-of-the-art PSi-OAT corrosion protection. This technology is fully compliant with the latest EU legislation.

5. Miscibility

How do I know which coolants can be mixed?

It is always recommended to use the OEM’s specified grade of coolant. This is important because whether you’re topping up or replacing your coolant, you need to understand which type you can safely use.

If you do not have the option of an equivalent specification, the table below demonstrates which types of coolant are miscible:

In the past, miscibility between coolants was even more strict. However, due to changes in coolant composition, the system has become more flexible.

Can I use the EVO LL for the coolant system of my electric vehicle or hybrid electric vehicle?

The versatility of the EVO LL allows for broad usage, but this coolant type is recommended to be used in ICEs (Internal Combustion Engines). Our recommendation is to use the dedicated range of E-coolants. This range has been designed specifically for cooling directly (FCEV) or indirectly the batteries of electric vehicles and offers all-around protection of metals. These include aluminium, cast iron, steel and stainless steel, and red and yellow metals, such as copper and brass.

For a hybrid electric vehicle, this is different because hybrids typically still make use of an ICE, in some cases as a main power source, but sometimes merely as a supportive range extender. For these applications, the EVO LL coolant can still be used.