70/30 vs. 50/50 Coolant– Which One Is Right for You?

Do you know anything special about coolants or antifreeze? This swirling, fluorescent liquid transfers heat and prevents engine damage due to freezing or boiling. Well, coolants are mostly called after the concentration ratio of their contents (glycol and water). The ratio can vary – with 50/50 and 70/30 being common mixtures.

Today, I will discuss 70/30 vs. 50/50 coolant to help you select them. In the case of 70/30, it means the coolant has 70% antifreeze and 30% water or vice versa. It can lower the freezing to -67°F and raise the boiling point to 235°F. Similarly, a 50/50 coolant mix has 50% antifreeze and 50% water. It can tolerate a wide range of -34°F to 265°F.

That was a brief overview of these two types of coolants. Hence, the contents and their ratios of coolants impact your car’s engine performance. For instance, water provides the best heat transfer, and glycol protects the engine from freezing. Apart from these two, other ingredients like corrosion inhibitors, antifoams, dyes, and other additives may be there.

Coolants & Concentration of Coolants

The cooling system maintains the engine temperature of a car. And the consistent circulating coolants through small channels in the engine block keep the system running. As the coolant travels through these channels, it absorbs the heat generated by the engine (1).

Coolant or antifreeze is a mixture of water, ethylene glycol, or propylene glycol besides the additives. However, An estimated 60% of engine downtime in the commercial trucking sector is coolant-related (2). So, choosing the proper coolant is essential.

This is where you need to consider coolant concentration and its types. In general, the two most common types are Inorganic Additive Technology (IAT) and Organic Acid Technology (OAT) (4).

IAT coolants are usually green with 2-3 years of longevity. Alternatively, OAT coolants can be orange, yellow, red, or purple. They can last up to 5 years. Besides IAT and OAT, the general types of coolants are synthetic, organic, and hybrid.

SyntheticTraditional formulaSuperior PerformanceLonger lifespanHigher price tag
OrganicMade of renewable resourcesEco-friendlyBiodegradable Requires frequent changes
HybridMixture of synthetic and organic formulaSuperb strength and performance Designed for most modern vehiclesModerate cost

Coolant Ratios

For sure, coolant ratios play a significant role in the performance and longevity of your engine. By ratio, we refer to the proportion of glycol to water in the coolant mixture. It is expressed as a percentage representing the antifreeze concentration in the coolant mixture. Let me give you an example.

Suppose you see a 70% coolant antifreeze ratio on your chosen product. The coolant mixture contains 70% antifreeze (glycol) and 70% water. Here, the antifreeze component lowers the freezing point of the coolant. Simultaneously, it raises the boiling point. The core purpose behind the ratios is to protect the engine at extreme temperatures.

You must maintain the correct coolant concentration. It affects the freezing and boiling points of the coolant mixture (3).

70/30 Coolant Ratio: Composition and Benefits

In 70/30 coolant, most of the mixture is made up of coolant. It refers to the ratio of antifreeze to water in the coolant mixture used in a vehicle’s cooling system. It has 70% antifreeze and 30% water. Using this coolant mixture, you can increase the freezing to -67°F and raise the boiling point to 235°F. So, it is suitable for extreme temperatures (5,6).

It is commonly composed of ethylene glycol or propylene glycol. These substances are less toxic if ingested. So, 70/30 is a safer option. Consequently, the high ratio of coolant to water provides enhanced freeze protection. So, if you live or drive under cooler conditions, I suggest you use this coolant.

However, note that the thermal capacity of antifreeze is not as high as water. This means that a 70/30 mixture is less efficient in conducting heat than a 50/50 mixture (7).

When to Use the 70/30 Coolant Ratio

The 70/30 coolant ratio is typically used when operating in icy environments. In such conditions, the temperature often drops significantly below freezing. This is because a 70/30 mix lowers the freezing point to -67°F – better than a 50/50 mix coolant. Hence, the engine can run too hot and overheat if the radiator’s cooling capacity is marginal (7).

50/50 Coolant Ratio: Composition and Benefits

This is also known as an antifreeze with the same ingredients (like ethylene glycol or propylene glycol) but with a different ratio. Well, 50/50 coolant refers to a 50/50 coolant refers to a coolant mixture that contains 50% antifreeze and 50% water (8). This ratio provides a balance between heat transfer and freeze protection.

Besides its cooling properties, the coolant contains ingredients inhibiting rust, corrosion, and scale (9). However, the exact chemical composition can vary depending on the manufacturers.

Many people use this antifreeze in automotive engines and HVAC systems. Typically, it is diluted with distilled water. Like I said, it can tolerate a wide temperature range -34°F to 265°F in a 15-psi pressurized coolant system (10).

One notable downside of this coolant is that it may not protect the engine in icy conditions. This is because it has less glycol or coolant properties than 70/30 coolants.

When to Use the 50/50 Coolant Ratio

In normal driving conditions, 50/50 coolants work better than 70/30 coolants. You can apply it in most climates. Also, the lubricant provides sufficient heat transfer and freeze protection for most vehicles. Also, it is easier to manage as it doesn’t require you to adjust the ratio based on the changing seasons.

The Comparison: 70/30 vs. 50/50 Coolant

So, you have learned about the coolants well. Now, I will help you understand the differences between these coolants.

Freezing Point

With a 70% glycol concentration, 70/30 coolant boasts a significantly lower freezing point. It can dip down to -67°F. It is like your vehicle turns out to be a polar bear, happily playing in the icy Arctic.

On the other hand, I mean, 50/50 coolant should not be underestimated. It can still protect your car’s engine against freezing, though it can reach down to -34°F.

Boiling Point

There is a saying – if you want, you must give. Similarly, 70/30 coolant sacrifices some heat-dissipating power, although it reigns in terms of withstanding cold. Its boiling point (235°F) is slightly less than 50/50. But you may not find any significant difference in most driving conditions.

Alternatively, 50/50 coolant, with its higher boiling point (265°F), can shine in warmer temperatures. It is ideal for most engines to transfer heat and avoid overheating efficiently.

Heat Transfer

Let me recall one thing. Pure water actually transfers heat better than glycol. Theoretically, 70/30 coolant has a slight edge in efficiency. Do not worry; glycol is there to work with water.

Now, think about the 50/50 coolant ratio. Its balanced mix can achieve optimal heat transfer in most engines (yours, too). This coolant will be a better idea for regular driving, particularly in summer.

Corrosion Protection

At this point, 50/50 coolant is the winner. The balanced components provide the ideal environment for the corrosion inhibitors in the coolant to do their work. So, this coolant can protect the metals of the car engine from rust and decay.

70/30 offers decent protection from corrosion. Still, its higher water content can increase the risk, particularly in older engines.

Final Words: 70/30 vs. 50/50 Coolant

So, who is the winner between these two coolants? Indeed, we were not in a boxing match with a clear K/O. As you can see, both antifreeze lubricants have strengths and weaknesses, so you can consider any of them best. But here’s a catch!

If you want to drive your car in extremely cold areas, 70/30 is a better choice. It is also a good choice for high-performance driving or carrying heavy loads because of its heat transfer capacity. For hot summers, 50/50 can be enough. Also, it is ideal for regular driving.

You can check the vehicle’s owner’s manual for recommendations from the manufacturer. Also, do not forget to check your coolant level and concentration to keep it within the recommended range. To do so, you can use a refractometer.

Remember, mixing different types of coolant can hinder the car’s performance. It may also increase corrosion in the radiator. In severe cases, it can corrode and damage the radiator, water pump, hose, cylinder gasket, and more.

That’s all for today! Thank you for your precious time!

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