How to Put Antifreeze in Your Car Safely

To put antifreeze in your car, simply mix it with water (or buy one that’s premixed) and top up your coolant reservoir to the fill line.
Written by Matt Terzi
Reviewed by Carrie Adkins
Topping off antifreeze is as simple as mixing antifreeze with water (or buying one that’s premixed) and filling the coolant reservoir to the fill line. Draining and filling antifreeze is a little more complicated, but both are great ways to save money on your car maintenance.
Antifreeze is an important fluid for the safe operation of your car’s engine. And unlike some of the other forms of car maintenance, this is one you can easily and safely do at home.
To help you through the process, the
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How to put antifreeze in your car

Whether you want to top off your reservoir or drain and refill your antifreeze from scratch, we’ve got you covered. But as with all things related to car maintenance, the first step is to ensure you’ve taken the right safety precautions.

Step 1: Review safety guidelines

It’s important to follow these safety guidelines. Failing to do so can result in injury or damage to your car. If you feel out of your depths, ask a mechanic to perform the maintenance for you.
  • Park your car on a flat, hard, even surface. Do not attempt vehicle maintenance on a hill or incline.
  • Turn your car off and allow it to cool down before you start. If the engine still feels warm, wait a little longer until it’s at a safe temperature.
  • Don’t wear loose clothing. Remove long shirts or jackets, roll up loose sleeves, and remove watches and jewelry while filling or replacing your antifreeze.
  • Use the parking brake. Before you jack the car up to drain old antifreeze, ensure the parking brake is engaged.
  • Use wheel chocks. Once the car is raised, set wheel chocks behind the back wheels to prevent it from moving.
  • Do not ingest antifreeze. Antifreeze is extremely toxic for both humans and animals. If you or an animal digests antifreeze, call poison control or dial 911 immediately.

Step 2: Check your antifreeze level

Pop the hood of your car and look for the coolant reservoir—a plastic tank usually on one side of the engine. If you can’t find it, consult your car’s manual. And keep that manual handy as you’ll refer to it frequently while replacing the antifreeze.
  • If the antifreeze in the coolant reservoir is below the fill line, you’ll only need to top it off
  • If the antifreeze looks brown or mucky, you’ll need to drain and replace the fluid
Some vehicles require a 50/50 mixture of antifreeze with water, while others take "premixed" antifreeze. Consult your vehicle’s owner manual to find the correct type of antifreeze for your engine.

Step 3: Gather your supplies

Here’s what you’ll need to top up your antifreeze:
  • The correct type of antifreeze as noted in your owner’s manual
  • Rag
  • Flashlight
If you’re draining and replacing the antifreeze, you’ll also need the following:
  • Car jack
  • Wheel chocks
  • Screwdriver or wrench (to open the engine bleed valves)

Step 4: Top up your antifreeze

If all you need to do is top up your antifreeze, it’s a simple process:
  • Using your rag, turn the cap on the coolant reservoir counter-clockwise—it’s usually pressurized, so don’t twist it too quickly and let the pressure escape before removing it
  • Fill up the reservoir with your mixed antifreeze to the fill line
  • Firmly replace the cap
If you instead need to replace the antifreeze, skip this step and move to #5.

Step 5: If needed, drain and refill the antifreeze

If your antifreeze is brownish or looks mucky, you’ll need to drain the radiator and fill it up with fresh antifreeze. This is more involved than just topping it off.
You’ll need to jack up your car and work underneath it. This can be dangerous work if you aren’t careful—so if you aren’t comfortable doing it, take your car to a professional for help.
Once your car is jacked up and you’ve set the wheel chocks in place behind the back wheels, here’s what to do:
  • Using your owner’s manual, locate the radiator’s petcock valve (also known as a drain cock valve)
  • Place your drain pan beneath the valve
  • Turn the petcock valve counterclockwise by a quarter or a half—your old antifreeze should start draining out
  • Once it’s done, close the valve tightly, lower the car down from the jack, and remove the wheel chocks
  • Set the starter to the "on" position so the battery activates—but don’t start the engine
  • Crank up your temperature and fan to their maximum settings, then turn the starter back off
  • Consult your manual to find any bleed valves your engine has and open them—this prevents air from getting trapped inside your coolant system
  • With your bleed valves open, slowly add your antifreeze mixture to the coolant reservoir
  • Stop when you reach the cold fill line and wait for 10 to 15 seconds for the fluid to settle, then continue filling
  • Stop filling when you’ve reached the fill line and it isn’t going down any further—if you see coolant exiting bleed valves, stop filling and close them
  • Once you’re done, close any open bleed valves and firmly replace the cap
Key Takeaway If you’re not experienced working underneath a car, antifreeze replacement is best left to a mechanic.

Step 6: Test everything out

Last but not least, test the engine to ensure everything is functional.
Double-check the reservoir cap is on and the bleed valves are closed, then start the engine and let it idle until it reaches its normal operating temperature—the temp gauge should be about halfway full.
Check your coolant reservoir again. If it dropped, turn the car off, give it a few minutes to cool down, and top off the antifreeze a little more. You may need to repeat this process a couple of times.
Check the reservoir again after 50 miles and top off as necessary. Otherwise, you should check the reservoir levels twice per year—once in the spring before it starts getting hot and again in fall before it starts getting cold.
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If you’re not afraid to get your hands dirty, topping off or replacing your antifreeze at home is a great way to save money on car maintenance. But if you’re really looking to save money, cutting car insurance costs is a great place to start.
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FAQs

What is antifreeze and what does it do?

Antifreeze, also known as coolant, is a liquid mixed with water that flows through your engine. It keeps everything at an optimal temperature—cooler in summer and warmer in winter.
Antifreeze prevents the water in your car’s cooling system from boiling or freezing and lubricates parts of your engine where motor oil isn’t used, like the water pump and coolant seals. It helps reduce engine corrosion, too.

Does the car need to be running when adding antifreeze?

The engine should be off and cool before adding antifreeze. After turning the engine off, let it sit for at least 30 minutes, though ideally a couple of hours.

How long after adding coolant can I drive?

Once your antifreeze is at the fill line, give it a few minutes to make sure it doesn’t recede. After that, you’re safe to drive again.
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