Is Your Coolant/Antifreeze Ready for Summer?

Extreme seasonal heat requires attention to the engine’s cooling system and coolant concentration

May 2015, - WebXclusive

by Colin Dilley, VP of Technology, Prestone

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Truck fleets that traverse the North American continent this summer, spanning regions from the North to the South and both coasts, know that one of the few constants among those thousands of miles of pavement will be stifling heat and oppressive humidity.

And if you happened to add additional antifreeze concentrate during the winter, how will that affect your heat protection when the temperature shifts? By increasing the percentage of concentrate during winter, heat exchange properties of the antifreeze/coolant are compromised and can lead to engine component troubles in the summer.

A disproportionate ratio of antifreeze/coolant to water in the mix can mean the heat exchange between it and the engine cooling system will not be efficient, putting additional stress on the cooling system components that could lead to premature failure. This can also lead to additional stress on the other functional fluids under the hood, including engine oil as well as transmissions and power steering fluids.

Components that could be affected include the radiator, heater core, wet sleeve liner, coolant pump, cylinder heat, thermostat, DEF valve, hoses, gasets, sensors, the EGR cooler and others.

OEM recommendations should always be consulted, but a general recommendation is a 50/50 ratio.

Measuring and maintaining the concentrate/water ratios within an engine cooling system can help ensure optimum engine operational efficiency. Ratios can be measured a number of ways, including a handheld refractometer, a hydrometer, or test strips.

The challenge for the fleet manager is that some measurements only ascertain whether boil point and freeze point protection are correct and do not indicate the level of inhibitor protection. Test strips are designed to test the inhibitor levels in a vehicle’s cooling system.

Testing kits, testing strips and refractometer like these from Prestone Command are essential tools for keeping antifreeze/coolant working properly all year long. Photo: Prestone.
Testing kits, testing strips and refractometer like these from Prestone Command are essential tools for keeping antifreeze/coolant working properly all year long. Photo: Prestone.

Having the ability to proactively test an engine cooling system is imperative to making the right decisions for maintaining the correct levels of antifreeze/coolant concentrations.

The heat of spring and summer will create harsh conditions and challenges to fleets across North America. Regularly scheduled maintenance throughout the lifetime of a heavy duty vehicle can keep it running for a very long time. Maintenance is the key to optimal engine cooling system operation, and fleet owners must monitor their antifreeze/coolant to ensure the concentrate remains at a safe ratio and the inhibitor levels are in the appropriate range.

For more information, check out the Critical Warm Weather Coolant white paper at:

This article was authored under the guidance and editorial standards of HDT's editors to provide useful information to our readers. Prestone Products Corp. manufactures and markets Prestone antifreeze/coolant and related products. Its U.S.-based Technology Center works closely with major engine manufacturers to create antifreeze/coolant formulations. More info at

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