Antifreeze versus coolant: What’s the difference?

Understanding the differences between antifreeze and coolant?

Though often used interchangeably, antifreeze and coolant are different. In the most simple terms, Antifreeze is the concentrated version of engine coolant. It must be diluted with distilled water before ti can be installed in a vehicle.

Coolant, on the other hand, is pre-diluted and can be poured directly into the reservoir without any dilution.

What’s in antifreeze and coolant?

The base ingredient is ethylene glycol (95%), which is used because it doesn’t freeze like water. In addition to the ethylene glycol, manufacturers add anti-corrosion, anti-foaming and lubricant additives to make up the other 5%.

How long does it last?

Or this image shows a fully corroded radiator caused by not changing coolant on time

The base ingredient never wears out, which is why some insist you never have to change your coolant. They’re wrong. Because the anti-corrosion, anti-foaming and lubricant additives do wear out, and when that happens, you get severe internal corrosion that eats away at the heater core and radiator, causing leaks.

Depending on the type of coolant used, the additives last two years or 24,000 miles for the older Inorganic Acid Technology (IAT) “green” coolants to as long as ten years or 100,000 for the latest organic acid technology (OAT) or hybrid organic acid technology (HOAT).

A leaking heater core can cost well over $1,500 to replace, making routine coolant replacement a no-brainer. Why risk those kinds of expensive repairs to save a few hundred dollars on a coolant flush at 100,000 miles?

How worn out coolant damages your cooling system

Notice the leaks on this heater car caused by not changing coolant on time

Engine cooling systems contain different metals like copper, aluminum, steel, and magnesium. When the anti-corrosion additives wear out, the antifreeze acts like a battery electrolyte, causing the metals to interact with one another, resulting in galvanic corrosion that eats away at the metals.

Skipping a coolant change can result in premature leaking and outright failure of the heater core (a $1,500 repair), water pump ($600 repair), radiator ($600 repair), or heater tube failure ($400 repair). If any of those components leak coolant and you don’t notice the leak in time, the engine can overheat, causing catastrophic engine damage in excess of $4,000. So it pays to change coolant on time.

©, 2016 Rick Muscoplat