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Choosing the right antifreeze/coolant to protect your vehicle in cold weather 

Posted January 8, 2023


As we live and work during the coldest months of the year, it’s useful to take stock of best practices for vehicle care during the winter months. What comes as a surprise to some is this fun fact: an engine’s antifreeze/coolant is just as important to the smooth functioning of a vehicle as the oil put into a fleet of trucks. Choosing the right antifreeze/coolant product for your vehicles can make the difference between an engine running smoothly and one that experiences serious problems during cold weather.

Whether your business uses a single vehicle or you have a small fleet of trucks, the basics of how to survive winter with the right type and ratio of antifreeze/coolant will be useful.  Be aware of all the aftermarket brands and formulations stocking the shelves and be cautious before you buy. It will be useful to take a closer look at what your vehicle is running on when the temperature drops.

How does antifreeze/coolant protect your fleet of vehicles?

Antifreeze/coolant is formulated to prevent corrosion inside a vehicle’s cooling system. It also helps to maintain optimal engine operating temperature regardless of whether you’re driving in the dead of winter or the heat of summer. Without the proper type, amount, ratio, and circulation of antifreeze/coolant, your engine can be in constant danger of freezing or overheating.  Inspecting and replacing the antifreeze/coolant in your vehicle at regular intervals will help prevent overheating, freezing, and premature cooling-system corrosion.

What is antifreeze made of?

According to Heavy Duty Trucking Magazine’s (HDT) Colin Dilly, the primary components of antifreeze, both glycol and water, can freeze. The perfect combination of the two, however, has the ability to prevent your engine from freezing at low temperatures.

How to inspect your antifreeze/coolant in three simple steps:

During extreme temperatures, it’s important to remain vigilant to ensure that the percentage of glycol in your antifreeze is sufficient to prevent engine freezing. HDT recommends following these three steps for checking the overall effectiveness of your antifreeze/coolant while also checking for seasonal freezing protection:

  1. Test your glycol for freeze-point
  2. Test your glycol for inhibitors to make sure you’re still getting the correct corrosion protection
  3. Make sure you have the right volume in your cooling system to prevent air pockets from forming

Three types of antifreeze/coolant and their uses

There are three types of antifreeze available: Inorganic Acid Technology (IAT), Organic Acid Technology (OAT), and Hybrid Organic Acid Technology (HOAT).

  • IAT is mainly used in older vehicles, is usually bright green, and has to be replaced every 30,000 miles.
  • OAT antifreeze/coolant is usually orange, yellow, red, or purple, and lasts much longer — 150,000 miles — but doesn’t contain any silicates or phosphates for additional engine protection.
  • HOAT antifreeze/coolant is typically orange or yellow and can last for 150,000 miles.

Antifreeze/coolant now comes in so many brands and formulations that you can’t rely on color alone to understand what you’re pouring into your engine. Almost all of it is pre-diluted with water for convenience, but using a pre-diluted product also means you’re paying more for less coolant.

Proper antifreeze/coolant ratios for cold weather

According to a recent article from The Automotive Training Center (ATC), in winter the correct antifreeze/coolant to water ratio is 60 percent antifreeze to 40 percent water. If you live in a very cold climate or experience a severe cold snap, the ATC suggests using 70 percent antifreeze to 30 percent water.

Switch to propylene glycol antifreeze/coolant to protect animals

Last but not least, many antifreeze/coolant products have ethylene glycol as their main ingredient. According to the Anatomical Therapeutic Chemical (ATC) Classification System, ethylene glycol is extremely toxic and has a sweet taste that can be appealing to both pets and wild animals.

To protect both your pets and any local critters, consider switching to antifreeze/coolant made with propylene glycol. It functions similarly as an ingredient, but is far less toxic.

All fleet cards are not the same, and different types of fuel cards suit the needs of different kinds and sizes of businesses. View WEX’s fleet card comparison chart to see which fleet fuel card is right for you.

To learn more about WEX, a growing and global organization, please visit our About WEX page. 

Editorial note: This article was originally published on March 18, 2019, and has been updated for this publication.

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Heavy Duty Trucker Magazine
Automotive Training Center