Back to Basics: What is Coolant and Why do I Need It?

Dec 20, 2017

Don’t Even Think About Skipping It

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Many drivers know their car or truck requires coolant – per recommendations in the owner’s manual – but they’re not always sure why.

“Today’s engines are often nestled in some tight engine compartments under a sleek hood that’s low, (the radiator is) pretty obstructed, the front end (of the car) for style reasons could be closed and (there’s) not much good air flow,” says Valvoline™ Technical Director David Turcotte. “So in modern cars, they would overheat in a matter of minutes if they didn’t have an active functional cooling system.”

Much like oil, coolant starts with the basic function of heat transfer and adds antifreeze protection. Then, depending upon the type of vehicle (car or truck), it may require specialized additives that are intended specifically for the needs of the manufacturer’s vehicle you have (particularly for imports), or for the type of mileage on your ride.

Coolant serves these primary purposes:

   •    Coolant transfers heat and keeps the engine operating. Its action prevents engine damage from freezing and boiling by keeping the liquid from forming a solid or a gas.  In order for heat to be effectively transferred, you need a liquid in the cooling system. If coolant freezes, it expands – and with that expansion comes breaking and cracking, which can lead to engine failure and damage. 

   •    If coolant boils, the gas/vapor formed does not transfer heat well, so metal could actually melt in the engine if you don’t keep liquid in contact with it in some places that need to stay cool. “That’s related primarily to the engine head,” says Turcotte. 

•     Coolant also protects metals and non-metallic elastomers (rubber parts and plastic parts in the engine and the cooling circuit).

According to Turcotte,“If you were just to use water and not operate the engine at all in the winter, as soon as it cools below freezing, the water will expand about 10 percent on freezing and makes a big old ice cube. That may fracture the cylinder heads, the block, and split open the radiator seams.”

Coolant tip 1

So, how do you choose a coolant? To begin with, always consult your vehicle’s owner’s manual for compatibility and warranty information. There are also several factors to keep in mind.

“When it comes to buying coolant, consumers oftentimes make their decisions based upon price rather than product performance,” says Turcotte. “When you go to retail outlets and find universal coolants, they’re like tube socks for anti- freeze, one size fits all – but it doesn’t work like that,” says Turcotte.

While many people simply want the cheapest form of coolant to maintain heat transfer and prevent freezing, it’s not that simple. Rather, coolants are formulated for specific vehicles, specific manufacturers and specific types of engines.

Think about this: In most cases, a car or truck is a major investment. Coolant is not an area to skimp. Trying to save small money may ultimately wind up costing big money in the end if your coolant or cooling system fails because the wrong type of coolant was used. Also, using undiluted coolant, pure water, a product that was not made specifically for vehicles, or a product that wasn’t recommended by the Original Equipment Manufacturer (OEM) can cause trouble.

That’s why the owner’s manual is so important to have as a reference, because it recommends the best coolant in order to keep the vehicle operating efficiently.

“Often times, people don’t think about the longer-term effects of corrosion and component damage,” says Turcotte. “Those can be latent: it can take six months to a year to get enough corrosion damage, deposits and plugging to create an issue from using the wrong coolant to have a visible problem. And by the time you get that problem, people have forgotten that they used the wrong coolant and think the radiator has simply failed as a part.  In reality, the radiator can be badly corroded and full of plugging internal deposits.  And then they have to buy a new one (radiator).”

coolant tip 2

But if the right coolant is chosen, there’s far less chance of problems occurring. 

“The coolant-related problems are inside the motor,” says Turcotte, “People don’t look in the motor, they don’t look at the cooling passages and the internal heat-transfer surfaces of the engine, so they have no idea of what a mess they can be making.”

Evolution of coolant has made significant gains over the past few decades. As Turcotte explained, two decades ago coolant was changed every couple of years. Then, about 10 years ago, the timeline extended to changing coolant every five years.

In many of today’s vehicles, coolant is designed to go 10 years, or up to 200,000 miles. Some vehicles are filled for life.

Valvoline develops coolants that last longer, can help reduce the cost of ownership and improve the lifespan of a vehicle, and protect crucial parts like gaskets and elastomers.

“Different engines have different materials of construction, different operating environments, variable flow rates, different peak temperatures and pressures, different elastomers, non-metallics and gaskets – and it all has to be protected,” says Turcotte.

“When choosing a coolant, be sure to pick the right one for each vehicle. The OEM does extensive testing and specifies what fluids, including coolants, should be used.” 

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