A Few Important Notes About Antifreeze

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In the late 1980s I had an opportunity to interview the two candidates running for the district eight seat in the U.S. Congress, then-incumbent Jim Oberstar and his GOP opponent, Jerry Schuster. My meeting with Congressman Oberstar began at his office in the Chisholm City Hall but quickly moved to the house he grew up in, where I chatted with his mother and daughters while he called his wife in D.C. It was interesting hearing his mother’s stories. One of which I found especially memorable: Jim’s dad was the first person on his block to own a car.

It was the mid-1930s, and they were proud of that new vehicle. In our modern lingo, you might call his dad an early adopter. Unfortunately, being an early adopter of new technologies means learning many lessons the hard way. If you know anything about northern Minnesota winters, you’re well aware it gets cold up here. Thirty below zero weather is normal, and 40 below zero is not uncommon. When water freezes it expands by 9 percent, and before too much winter elapsed, that beautiful new car had a cracked engine block. They hadn’t yet learned about antifreeze. Nevertheless, even though they couldn’t drive it after that, Jim’s mother told me it sure looked nice sitting in their front yard. They were still the only people on their block to own a car.

I share this story because it’s a reminder of why antifreeze is still important. Engines today may be more sophisticated, but they still don’t have any flex when it comes to water freezing in their veins. Antifreeze is as important today as it ever was.

It’s interesting to me that engines can fail both by getting too cold, as in the story above, or by becoming too hot. Both situations can result in a terminated power plant. The whole point of the cooling system is to keep the latter from happening. The main elements in this cooling process are the thermostat, the fan, the radiator itself and the fluid, which we will address here.

Antifreeze consists of three primary components: water, glycol and additives. Water is an excellent heat-transfer fluid, but with it comes some inherent issues such as freezing and corrosion. Glycol is the chemical compound added to lower water’s freeze point. Additives are added to protect against corrosion while providing a number of other functions, including cavitation protection, pH control, lubrication and anti-scaling.

The glycol used in antifreeze is either ethylene glycol (EG) or propylene glycol (PG). The most common is EG, which has a slightly better freeze point and a small advantage in heat transfer when compared at a similar mix ratio. It is also less expensive, making it the popular choice. Because EG is hazardous, however, a bittering agent is added to the antifreeze to discourage ingestion. PG is the more environmentally friendly choice and is safer to use around children, pets and wildlife because it is biodegradable and has low toxicity. Thus, some applications and locations require PG formulations.

Additives Differentiate Antifreeze Performance

There are three categories of additives, and they can all be blended with the two glycols mentioned above.

•  Inorganic salts: The first additive type is found in the old, green, conventional antifreeze product. These products use inorganic salts, such as nitrites, phosphates and silicates, to provide protection against corrosion and cavitation, among other things. Inorganic salts work by forming a sacrificial layer over all components, and they are fast-acting. Unfortunately, some of these are bad for the environment, and they deplete quickly, typically only lasting two years or less. Once they are depleted, they can start working against you by causing aluminum corrosion and deposit issues. Inorganic salts can also be incompatible with each other, leading to a dropout substance in the form of an abrasive or slime. For these reasons, automotive OEMs have moved away from this type of antifreeze, and they have banned the use of certain inorganic salts.

•  Organic acids: The next additive type is the high-performance choice called organic acids, often referred to as organic acid technology (OAT) or poly organic acid technology (POAT). Organic acids are only used when and where they are needed. This results in much longer-lasting protection. They also do not have the dropout, scale deposit or compatibility issues inherent to inorganic salts. Therefore, this type of antifreeze can be used in a wide variety of applications, even for mixing with other types of antifreeze as top-off.

•  Hybrids – The final option available is a combination of the previous two, appropriately called hybrids or hybrid organic acid technology (HOAT). These are a mix of inorganic salts and organic acids. Once the inorganic salts deplete, the organic acids take over. HOAT products provide a blended performance result by alleviating some of the issues with inorganic salts by limiting the quantities and relying on the organic acids to boost long-term performance. The inorganic salts used in these products vary by application because automotive OEMs have banned various salts from their products due to performance issues. For example, Asian OEMs don’t allow any silicates because they tend to drop out, forming hard particles that can cause seals to leak. They can also lead to scale deposits that insulate surfaces and lead to overheating.

Last Thoughts

Radiators play a critical role in the performance of an engine, removing excess heat and thereby ensuring the engine can function properly. Radiator fluid, a.k.a. antifreeze/coolant, is an essential part of this equation your customers shouldn’t take for granted.  


ED NEWMAN is the advertising manager for AMSOIL INC., an independent manufacturer of synthetic lubricants. He’s been writing articles about synthetic oil since 1986. He can be contacted at enewman@amsoil.com. For more information, visit: www.amsoil.com


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