Coolant and Climate: Adapting Your Coolant System for Extreme Weather

Extreme weather conditions pose huge questions for those in the heavy-duty trucking industry. These conditions must be considered when maintaining your truck’s vital systems—especially the coolant system- whether it's blistering heat or freezing cold. Adapting this system to these conditions is crucial to safeguarding your engine and performance on the road, regardless of the weather outside.

This article will delve into the critical role of coolant in heavy-duty vehicles, explore its impact under extreme weather conditions, and provide actionable tips for coolant system checks, adjustments, and troubleshooting.

Understanding Coolant and Its Role

Coolant is a vital fluid that circulates through your engine's cooling system. It performs two key functions:

Heat Transfer: Coolant absorbs heat from the engine block and cylinder head as the engine runs. This hot coolant then travels to the radiator, where it releases the heat into the surrounding air through the radiator fins.

Corrosion Protection: Coolant contains additives that prevent rust and corrosion from forming on internal engine components.

Types of Coolant

Organic Acid Technology (OAT): OAT coolants are extended-life coolants known for their excellent corrosion protection and long service intervals. Due to their durability, they are a popular choice for heavy-duty vehicles.

Hybrid Organic Acid Technology (HOAT): HOAT coolants combine the properties of OAT coolants with traditional coolants. They offer good corrosion protection and can be mixed with certain coolants in an emergency.

Inorganic Acid Technology (IAT): IAT coolants are traditional coolants that are less expensive than OAT and HOAT options. However, they require more frequent changes due to their shorter lifespan and lower corrosion protection capabilities.

Always consult your vehicle's owner's manual to determine the recommended type of coolant for your specific engine. Using the wrong coolant can compromise its effectiveness and even damage your engine.

Impact of Extreme Weather on Coolant Performance

Hot Climates: High temperatures can cause coolant to break down and evaporate more quickly. This can lead to overheating and reduced system efficiency. In hot climates, more frequent coolant system checks and top-offs are essential.

Cold Climates: When temperatures drop below the freezing point of your coolant mixture, it can freeze and solidify. This can block coolant flow, leading to engine damage. Ensuring your coolant has adequate antifreeze properties is crucial in cold weather to prevent freezing and protect your engine.

Monitoring and Maintenance Best Practices

Here are some key practices for maintaining a healthy coolant system throughout the year, no matter the temperature.

Regular Check-ups: Regularly inspect your coolant system for leaks or damage. This includes checking the radiator hoses, clamps, and radiator cap for cracks, tears, or loose connections. A visual inspection of the coolant reservoir can also reveal any discoloration or debris, which could indicate contamination.

Coolant Testing: Coolant testing kits are readily available and allow you to measure the coolant's effectiveness easily. These kits typically test for freeze protection and reserve alkalinity (RA). The freeze protection level determines the lowest temperature at which your coolant will freeze. 

Reserve alkalinity (RA) indicates the coolant's ability to neutralize engine acids and maintain its corrosion protection properties. If the test results fall outside the recommended range, it's time to replace the coolant.

Adjusting Coolant Composition: As the seasons change, you may need to adjust the mix of water and antifreeze in your coolant reservoir. Your owner's manual will provide the recommended coolant-to-water ratio based on your region's expected temperature range.

Coolant Management Policies: Establish or review your existing coolant management policies for your fleet. These policies should outline proper coolant maintenance procedures, including recommended service intervals for coolant changes and system checks.

Training for Drivers: Educate your drivers on the importance of the coolant system and how to recognize potential issues. Training should cover basic coolant system checks, such as checking the coolant level and for leaks, as well as signs of overheating and coolant contamination. Empowering drivers to identify these issues early on can help prevent breakdowns and costly repairs.

Troubleshooting Common Coolant Issues

Overheating: Overheating can be caused by a variety of factors, including low coolant levels, a faulty thermostat, or a clogged radiator. If your truck starts to overheat, pull over to a safe location and turn off the engine. Do not attempt to add coolant to an overheating engine! 

Let the engine cool down completely before checking the coolant level. If it is low, top it off with the proper coolant mixture. If overheating persists, consult a qualified coolant system mechanic to diagnose the problem.

Contamination: Oil or other contaminants in the coolant can significantly reduce its effectiveness and lead to corrosion. Signs of contamination include a brown or murky appearance of the coolant, a greasy film on the coolant reservoir, or a loss of coolant performance. If you suspect coolant contamination, it's essential to have the entire cooling system flushed and refilled with fresh coolant. 

Low Coolant Level: Several factors, including leaks, a faulty radiator cap that isn't sealing properly, or even normal coolant evaporation over time, can all cause low coolant levels. The resolution here depends on the severity of the issue:

  • Small Leak: If you identify a small leak in a coolant hose or clamp, you may be able to temporarily fix it with a coolant system patch or a hose clamp replacement. However, a permanent solution involves replacing the faulty component.
  • Faulty Radiator Cap: A faulty radiator cap that doesn't maintain pressure can allow coolant to boil over at a lower temperature and contribute to coolant loss. Replacing the radiator cap is a relatively inexpensive fix.
  • Normal Evaporation: Coolant does evaporate to a small degree over time. If the coolant level is slightly low due to evaporation, simply top it off with the proper coolant mixture according to your owner's manual. Remember, never add coolant to an overheating engine. Let it cool completely first.

Clogged Radiator: Over time, the radiator fins can become clogged with debris, such as leaves, insects, or road grime, reducing their ability to dissipate heat and causing overheating. A professional can often clean a clogged radiator using a specialized radiator flush service. In severe cases, the radiator may need to be replaced.

Faulty Thermostat: A stuck-closed thermostat can prevent coolant from circulating properly, leading to overheating. On the other hand, a stuck-open thermostat can allow coolant to flow too freely, preventing the engine from reaching optimal operating temperature, which can reduce fuel efficiency. A faulty thermostat needs to be replaced to ensure proper coolant circulation and engine temperature control.


By understanding the critical role of coolant and implementing proper maintenance practices, you can guarantee that your vehicles run strong mile after mile, regardless of the weather conditions. Regular coolant system checks, adjustments based on seasonal changes, and prompt attention to any warning signs will go a long way in preventing breakdowns and extending the life of your engine.

Need to schedule a service?
Call us today!

Service Request

More Articles

Avoiding the Red Zone: How Coolant Systems Prevent Engine Overheating

Avoiding the Red Zone: How Coolant Systems Prevent Engine Overheating

Discover how truck coolant systems prevent engine overheating, the role of radiators, water pumps, and fan clutches, and maintenance tips to keep your fleet running smoothly. Contact National Fleet Management in Charlotte, NC, for expert coolant system services.
Read more
Upgrading Your Heavy-Duty Coolant System

Upgrading Your Heavy-Duty Coolant System for Extreme Performance

Heavy-duty vehicles need a robust coolant system upgrade to maintain proper engine temperature and ensure peak performance in demanding conditions.
Read more