The Specs: How Does Coolant Actually Work?

Learn About What’s Inside and How to Choose the Right Product

Okay, you’re ready to change the coolant in a vehicle. To begin with, always consult your vehicle’s owner’s manual for compatibility and warranty information and Original Equipment Manufacturer (OEM) recommended coolant.  Here are some tips to better determine the right coolant.

Selection depends greatly on the type of vehicle. In general, if it’s a new car, there may really be no need to change the coolant for a long time – in some cases 10 years or 200,000 miles, according to Valvoline™ coolant experts. But you still need to keep the system topped off and check its freeze protection regularly.

In older cars there are various types of coolant that in many instances are made precisely for your mode of transportation as recommended by the OEM.

Surprisingly, even with all the technology that has evolved since the first car was built over 100 years ago, as powerful as engines can be, they’re also inefficient – particularly when it comes to generating and dispersing heat.

“When you burn fuel in an engine, about one-third of the energy produced actually goes into propelling the vehicle,” says Valvoline Technical Director David Turcotte. “About a third of it is dissipated through the exhaust as heat, and the other third is removed by the cooling system to keep the engine running without overheating.”

According to Turcotte, “the point is the combustion process is inefficient and generates significant excess heat. So, some of it can just freely blow out the exhaust, but some of it we have to actively capture and remove with the liquid (coolant) and cooling system.”

Approximately 90 percent of concentrated coolant's makeup is ethylene glycol – which has been the industry standard for more than 70 years – along with a balance of additives such as corrosion inhibitors, pH modifiers, scale inhibitors, buffers, dye, defoamers, and bittering agents.

How to Read the Labels

One of the best additives used is silicate.

“Silicate is a wonderful corrosion inhibitor,” Turcotte said. “It’s great on aluminum, which most engines and cooling systems are made of today. But it helps with all the metals of the cooling system, so it’s a great inhibitor. A lot of manufacturers use it in their anti-freeze.”

Interestingly, where cars are manufactured sometimes plays a role in whether or not the coolant contains silicate. While European OEMs mostly use silicate-containing coolants, those in Asia – primarily in Japan – use silicate-free coolant.

Another key Valvoline additive is Alugard™, a compatibility agent that helps when mixing coolants for broader application.

That’s why, in addition to Zerex™, Valvoline makes MaxLife™ Antifreeze/Coolant, a convenient high mileage coolant that contains Alugard, with an ability to work in a variety of different vehicles across the board.

There’s also Dex-Cool™, which is formulated specifically for General Motors vehicles, but can also be used in Ford and Chrysler products.

Coolant comes in a variety of colors, often keyed to the level and type of protection it offers – from basic (typically green in color) to more advanced- and specific-usage coolants that can have hues including red, orange, purple, green, yellow, or blue, all designed to keep your vehicle operating optimally and from overheating.

However, Turcotte cautions, if your car is still under warranty, do not replace, say, a violet-colored coolant with yellow Universal or some other different colored coolant.

As coolant has evolved, so have the recommendations on what type of coolant/water mixture should be used. It used to be that coolant manufacturers recommended a mixture of 50 percent coolant and 50 percent water be put into vehicle radiators.

Now that mixture can vary from 40 to 70 percent coolant. At the top end is 70 percent coolant (with 30 percent water), which protects radiators and coolant systems all the way to -84 degrees Fahrenheit. However, excepting geographies with extreme cold temperature, you can go as light as 40 percent coolant (60 percent water) in temperate climates. Or, if you prefer to go back to the tried-and-true 50-50 coolant/water mix, you can be covered all the way down to -34 degrees Fahrenheit.

Choosing Between Valvoline Coolants

This leads us to Valvoline coolant products and the purposes they serve:

Valvoline Coolant Guide

Much like picking which clothes to wear to match the weather, pick wisely when choosing coolant. Your car will stay cool and operate at peak efficiency.


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