How To Put Coolant In Your Car (+Symptoms, Types & FAQs)

The weather’s been extremely hot, and you’re about to go on a road trip. To be safe, you decide to check on your coolant— and it’s low!

Wait, how do you safely add coolant to your car?
If this is your first time refilling coolant, we have the right guide for you.

In this article, we’ll walk you through the steps to add coolant to your car, describe signs of low coolant levels, explain the different types of coolant available, and answer some FAQs.

Let’s begin.

How to Put Coolant In Car (Step-by-Step)

You should check your coolant level at least every month to prevent your car from running out of it and from potentially overheating while on the road. Plus, refilling the engine coolant only takes a few minutes.

Here’s what you’ll need to refill the coolant in your car:

The correct type of antifreeze or coolant mixture
Distilled water
Rag
Funnel (optional)

Warning: Antifreeze is poisonous to humans and animals. Thoroughly clean up any spills and properly discard the old fluid. Also, keep pets and small children out of the area whenever you work with antifreeze.

Now, here’s how to add coolant to your car:

Step 1: Park Your Car and Turn Off the Engine

First, park your car on a level surface, and put your parking brakes on. This prevents the car from moving when you’re working on it.

Also, if you’ve just used the car, let the hot engine cool off before you begin.

Why?
Adding coolant to a hot engine is dangerous, and you’d risk burning yourself with the hot coolant vapors. Although adding coolant while the engine’s still running is possible, you’ll need to add it through the expansion tank instead of the coolant tank.

Step 2: Locate the Radiator and Coolant Reservoir

After the car’s cooled off, open the hood to find the car’s radiator and coolant reservoir in the engine bay.

The reservoir is typically located on the right side of the engine compartment. It’s a translucent-white container with a metal or black lid with “Caution Hot” written on it.

You can find the radiator right in front of the engine. If you’re having trouble locating the two, refer to your owner’s manual to help find them.

Step 3: Inspect the Coolant Level in the Reservoir

To inspect your coolant level, observe the “Min” and “Max” scales on the side of the reservoir. If the fluid level is within these lines, you’re fine, but if the coolant level is closer to the “Min” scale, you’ll need to add coolant.

Don’t forget to check the coolant level in the radiator as well. You can open the pressure cap and take a quick look inside.

Another thing to note is the coolant color — unscrew the reservoir cap and peep into the coolant tank. Regular coolant should be clear and has the same color as fresh coolant. If it’s dark, brown, or sludgy, schedule a coolant flush with your mechanic.

Note: Only proceed if the coolant level is low and the coolant doesn’t appear contaminated or too old. Contact your mechanic immediately if you suspect a leak or broken hose is causing the low coolant.

Step 4: Prepare the Coolant Mixture (Optional)

You can easily get your hands on premixed coolant mixtures at the store.

But if you’re a DIY enthusiast and wish to make it yourself, here are some things you should remember:

Always use the right coolant type
Follow the manufacturer’s instructions when diluting concentrated antifreeze to make the coolant mixture.
Only use distilled water, and avoid tap water
Properly store any excess coolant or antifreeze, and seal the bottle tightly

Pour a 1:1 ratio (50/50) of antifreeze and distilled water into a container and mix it well to prepare the coolant mixture (unless the manufacturer instructions say otherwise).

Now that the coolant mixture is ready, time to pour it in!

Step 5: Pour the Coolant into the Reservoir and Radiator

Use a funnel to pour the coolant into the tank. Pour in just enough until it reaches the “Max” line.

The same thing goes for the radiator. If your radiator doesn’t have a fill line or you can’t find it, pour the coolant in until you can see it reach the bottom of the filler neck.

When filling the coolant reservoir and radiator, ensure you don’t overfill it — hot coolant expands and takes up more space. Keeping your coolant at the correct level helps to keep your radiator in working condition.

Once the coolant tank and radiator are full, screw the radiator cap and reservoir cap back on until it clicks.

Step 6: Perform an Overheating Test

When all that’s done, close your hood and restart your vehicle.

Allow your engine to run until the temperature gauge rises to normal operating engine temperature, and conduct an overheating test.

To do that, drive your car around the neighborhood for 30 minutes or even to the nearest convenience store. If your engine overheats during the test drive, immediately stop driving and turn off the engine. This means that there’s something wrong with the cooling system.

The causes may vary from a coolant leak, a blown head gasket, a stuck water pump, or a leaking radiator hose. At this point, it’s best to get your coolant system checked out by a professional.

Next, let’s learn how to spot low coolant levels without accessing the engine bay.

Symptoms of a Low Coolant Level

The symptoms of low coolant levels include, but aren’t limited to:

Unusually high temperature gauge readings
Engine overheating
Bright-colored fluid leak under the car (coolant leak)
Grinding or gurgling noises coming from the engine compartment (the radiator is filled up with air due to very low coolant)
Sweet-smelling steam coming out of the engine

Note: The symptoms above will show if your car is severely out of coolant. If this happens, immediately find a safe parking place and shut the engine off. Contact your mechanic and schedule for car maintenance.

Now, remember we mentioned getting the right type of coolant before refilling the tank?
Let’s see what they are.

Different Types of Engine Coolant

Car engines come in a variety of horsepower, durability, and sizes. These differences call for different coolant types.

(Also, coolant is a mix of antifreeze and water, which is why you’ll see the terms used interchangeably.)

There are three main types of coolant fluid:

A. Inorganic Additive Technology (IAT)

IAT coolants are made with ethylene glycol + phosphates and silicates. It’s also known as traditional coolant, is typically green in color, and is used by older vehicles.

It’s great at preventing engine corrosion but not at removing debris.

B. Organic Acid Technology (OAT)

OAT is another coolant type made using propylene glycol and is usually orange. It contains organic acids and corrosion inhibitors, giving it extended service life.

It protects against heat damage (corrosion, head gasket degradation, cylinder head distortion, boil-overs, etc.) for all engine types, including diesel engines.

C. Hybrid Organic Acid Technology (HOAT)

A relatively modern coolant type, HOAT coolants combine the first two types. Depending on the brand and manufacturer, HOAT coolants come in various colors (pink, orange, yellow, blue, etc.)

To date, there are three types of HOAT coolants:

Phosphate-Free Hybrid Organic Acid Technology: Turquoise in color and contains organic and inorganic corrosion inhibitor chemicals.

Phosphated Hybrid Organic Additive Technology: Blue or pink, contains corrosion inhibitor chemicals like phosphates and carboxylates.

Silicated Hybrid Organic Additive Technology: Bright purple and contains silicates that prevent engine corrosion.

So the next time you get coolant for your car, ensure you get the right one.
Answers to some FAQs are up next.

5 FAQs on Engine Coolant

Here are the answers to some common questions on engine coolant to help you understand better:

1. Are Coolant and Antifreeze the Same?

No, they aren’t.

Although the terms are used interchangeably, the two fluids are different.
Here are their differences:

Composition: Antifreeze is a concentrate made from glycol-based chemicals, while coolant is a mixture of water and antifreeze.

Function: Coolant maintains your engine temperature and prevents overheating, while antifreeze is the main component in the coolant that keeps it from freezing in cold climates.

How it works: Coolant absorbs engine heat by circulating throughout the engine and radiator hose and gets cooled off by the radiator. Antifreeze raises the boiling point and lowers the freezing point of the coolant to ensure it doesn’t freeze or boil in the engine.

Both fluids are essential to keep your engine running properly despite the differences. So make sure to refill your radiator and coolant reservoir when needed.

2. Can I Use Water to Top Up My Coolant?

Using water to top up your coolant isn’t advisable, but if it’s the only thing you have, then it should be alright. You shouldn’t do this too often, as it could contaminate the fluid and leave mineral deposits inside the engine and radiator or cause moss build-up in the coolant system.

A better option is to use distilled water, which doesn’t contain the contaminants that can damage your pipes.

3. What Temperature Should the Coolant Be in My Car?

A safe coolant temperature should be between 160 °F and 225 °F. Although your engine can still function outside the appropriate range, driving at such temperatures could cause internal engine damage.

Overheating could lead to engine knocking, increased fuel consumption, cylinder head damage, and head gasket failure. Meanwhile, a cold-running engine can reduce engine performance, struggle to accelerate, and stall.

4. How Often Should I Replace My Car’s Coolant?

Most manufacturers would recommend a coolant flush after every 30,000 to 70,000 miles.

You don’t need to wait until your car reaches the recommended mileage to flush out the old coolant. If the coolant in the reservoir appears very dark, has metal specs, or looks sludgy, then it’s high time you schedule a coolant change.

5. Can I Mix Different Types of Coolant?

Mixing different coolant types or adding the wrong kind of coolant will impair the coolant’s performance.

Different coolant types are made with different chemicals to ensure it doesn’t damage the engine block and hinder its performance. Adding different coolants to your engine would cause their additives to react differently, causing the radiator and other engine block components to corrode.

Final Thoughts

Adding coolant to the engine is an important car maintenance procedure. Ensuring your car has enough coolant can help prevent overheating and other related issues.

However, if your coolant looks dirty or there are fluid leaks, contact a professional to check it out— like AutoNation Mobile Service!

AutoNation Mobile Service is a mobile auto repair service you can get with a few taps on your phone. We offer a range of quality car maintenance services and are available 7 days a week.

Contact us today to get your coolant replaced or fix any cooling system issue you have, and we’ll send our best mechanic to help you out.