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What Does Antifreeze Do & How Do I Use It?

BY: Keith Benline
A person changing their vehicle's coolant.

The holiday season is a time many look forward to. After all, it gives people a chance to see their friends and family, spread cheer, or even take a much-needed break. Yet, while all of these are things almost anyone can look forward to, the season also brings about frigid weather and winter driving conditions enough to make any yearn for spring and summer. 

Just like these chilly temperatures can cause stress, the same can be said for your car, like the extra stress on your car’s radiator and the antifreeze inside. But antifreeze is one of those automotive fluids that car owners take for granted. With that in mind, let’s review how this essential liquid helps a car engine and makes cold-weather driving possible, as well as some of the critical differences between antifreeze and engine coolant.

What is Antifreeze?

Antifreeze is a solution that keeps a car engine operating properly when temperatures drop to freezing and below. In short, this liquid, which is based on ethylene glycol or propylene glycol, helps keep the engine at an optimal operating temperature, regardless of what the weather is doing. 

At the same time, antifreeze also helps prevent an engine from overheating, hence why it is often referred to as “coolant.” Most vehicles use a year-round “coolant” mixture that’s half glycol (ethylene or propylene) and half distilled water, but a formulation with a mixture of antifreeze (70%) and distilled water (30%) can be used for extreme winter temperatures. Undiluted “antifreeze” comes in different colors, which should never be intermixed, to signify different formulations and uses. 

Overall, antifreeze (regardless of the dilution percentage) is the critical element of an engine’s cooling system, which manages the high temperatures generated by an internal combustion engine. This liquid flows alongside the engine to extract the heat and travels back to the radiator to get cooled. Some heated antifreeze also passes over the heater core, which is used to warm the cabin. 

Poor-quality antifreeze or a low antifreeze level can cause engine problems during the winter. In fact, overheating is typical, even in cold temperatures, as the ailing antifreeze (or a lack of it) cannot regulate engine temperature. Extreme overheating can lead to even more extensive damage, like a cracked engine block

There’s another benefit to maintaining a sufficient level of quality antifreeze. Because of anti-corrosion additives, key parts of your engine and coolant system (like the cylinder head, head gasket, and water pump) are protected. 

How Do I Use Antifreeze?

Antifreeze usage comes down to knowing where to put it in your car. It’s a process that a driver should be familiar with, just like refilling the gas tank or adding engine oil. 

It’s also important to note that while all water-cooled engines (“water” really means antifreeze or coolant) operate similarly to help keep your engine cool, it’s essential to know that each automaker’s approach can vary. In other words, how you put antifreeze in a Ford may be somewhat different from how it’s done in a Toyota, so always follow your manufacturer’s recommendation, like checking your owner’s manual for the right type of antifreeze your car needs

How to Check/Change Your Car’s Antifreeze

Let’s review what’s involved in checking or replacing a car’s antifreeze. For the most part, these steps are straightforward and a DIY affair. However, don’t hesitate to seek professional help if you’re uncertain or uncomfortable doing anything with your vehicle.

Importantly, NEVER open the radiator cap on a hot cooling system. It’s under pressure and can spew scalding steam and coolant, which could severely burn or injure you. 

1. Review the Owner’s Manual

A close-up image of a car's radiator cap. Car owners should never open their car's radiator cap while the engine is hot, as it poses a severe burn risk.

Checking antifreeze begins with a look at the owner’s manual. These details will show you where to locate the coolant reservoir, a tank connected to the radiator that stores antifreeze. In modem cars, antifreeze is added through the coolant reservoir, not the radiator

At the same time, take note of the manufacturer’s antifreeze specifications. The manual will detail the precise type and formulation to use. Follow this information to the letter. If you can’t find your car’s owner’s manual in the vehicle itself, many automakers have copies available to view online, or you can contact them to inquire about getting a new copy.

2. Look at Service Records

This is also an excellent time to check the service records for the last time the antifreeze was changed and the last time you took care of other necessary maintenance tasks. Antifreeze replacement timeframes vary by manufacturer, but this is generally recommended every 30,000 to 70,000 miles. 

3. Check Antifreeze Level and Condition

Look at the coolant reservoir to see if there’s sufficient antifreeze in the system. A horizontal line on the tank housing will determine the maximum fill level. At the same time, look at the color of the antifreeze; it should be bright green, yellow, orange, red, blue, or pink. If the antifreeze color is muted or brownish, it’s probably time to replace the fluid. 

Getting an antifreeze tester is also a good idea; they’re inexpensive (less than $10) and can confirm if the liquid is still functional. The tester withdraws a small amount of antifreeze to check the solution/water ratio and temperature effectiveness (boiling point and freezing point).

4. Inspect the Engine Cooling System

While in the engine compartment, look for any signs of a cooling system leak. You may notice antifreeze accumulations outside the reservoir tank, near the radiator, or on other engine components. See if any antifreeze is dripping onto the ground. Any possible leaks should be looked at right away by a professional mechanic. If you can’t see any indications of a leak, still check the antifreeze levels. If they are low, look to top them off. 

5. Add Antifreeze

If you notice that your vehicle needs antifreeze, adding it is a simple process. Open the reservoir lid and add antifreeze until the maximum fill line is reached. A funnel, while not required, will help keep things neat. Be sure the antifreeze is mixed to the correct ratio detailed in the owner’s manual (some antifreeze comes premixed). Take note that antifreeze is toxic, so wipe up any spillage, so pets or children do not ingest it. 

6. Replace Antifreeze

If your car’s antifreeze is past its prime or overdue for scheduled maintenance, it’s time to replace it. It’s a job readily handled by a DIYer with modest skills; however, it makes sense to have this done at a service center for a straightforward reason: disposal of the old antifreeze. This liquid shouldn’t be poured down the drain or disposed of in the garbage. Old antifreeze should be handled by a recycling center or an auto repair shop dealing with hazardous chemicals. 

Replacing antifreeze involves: 

  • Draining the old solution
  • Adding a conditioner to treat corroded interior surfaces
  • Emptying and properly disposing of the conditioner
  • Refilling the cooling system with the correct antifreeze

Get Year-Round Protection with Endurance

Like regular oil changes, car washes and more, ensuring your car has antifreeze, and the proper coolant levels are vital to maintaining any vehicle. Yet even following your car’s essential maintenance schedule down to the fine print can’t prevent every breakdown or repair. And for those with cars outside their factory warranty coverage, it’d be up to you to pay for all that yourself—but not when you have an Endurance auto protection plan.

Endurance offers a wide range of coverage options starting at $79 per month. There are even plans to help protect vehicles that most other providers won’t cover, including high-mileage vehicles, select luxury models, salvage or rebuilt title vehicles, and more. Plus, regardless of your plan, all Endurance customers receive 24/7 roadside assistance, rental car reimbursement, and trip interruption coverage. Other benefits include:

Plan holders are also eligible for one year of free Elite Benefits. A small enrollment fee opens up to $2,000 of valuable services, including tire repairs and replacements, collision repair discounts, and key fob replacement. 

To find out more about how Endurance can help you, call our award-winning customer service team at (800) 253-8203 to request a FREE quote or shop online today. You can also check out the Endurance blog to discover other helpful articles on topics ranging from DIY car care, expert maintenance and buying advice, extended warranty coverage comparisons, and more. 

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