How to Top Off Car Coolant

Coolant, also known as anti-freeze, is vital to your car engine’s health. The cooling system is responsible for transferring the heat created within the engine during combustion to the atmosphere. Coolant mixed with water in typically a 50/50 mix, circulates through the engine, absorbs heat, and flows to the radiator via the water pump and cooling passages to shed the heat. Low coolant levels can lead to the engine running hotter than designed and even an overheat condition which can damage the engine.

Part 1 of 1: Check and top off coolant

Materials Needed

  • Coolant
  • Distilled water
  • Funnel - not required but keeps from spilling coolant
  • Rags

  • Tip: Be certain to use the approved coolant for your vehicle and not the “approved for all vehicle” types. Sometimes the chemical differences between coolants can lead to a “gelling” of the coolant and clogging of smaller coolant passages within the cooling system. Also, buy straight coolant and not the 50/50 “pre-mixed” versions. You will be paying nearly the same price for 50% water!!

Step 1: Check the coolant level. Start with a cool/cold engine. Some vehicles do not have a cap on the radiator. Checking and topping the coolant is done strictly from the coolant reservoir. Others may have both a radiator and coolant reservoir cap. If your vehicle has both, remove them both.

Step 2: Mix coolant and water. Using an empty container, pour a 50/50 mixture of coolant and distilled water into it. Use this mixture to top off the system.

Step 3: Top off the radiator. If your vehicle has a cap on the radiator and no coolant is visible in the radiator, top it off until you see coolant at the bottom of the filler neck. Give it a moment to “burp” as there may be air trapped below. If it “burps” and the level drops a bit, fill it again to the bottom of the neck. If the level remains the same, replace the cap.

Step 4: Top off the coolant reservoir. The reservoir will be marked with MIN and MAX level lines. Fill the reservoir to the MAX line. Do not overfill it. The coolant mixture expands as it heats up and needs room to do so. Replace the cap.

  • Note: Even without a leak in the system, coolant levels can drop over time simply from boiling off. check the coolant level after a day or two or driving to verify the level is still correct.

If your low coolant light comes on or your vehicle is leaking coolant, have a mobile technician from YourMechanic inspect your cooling system at your home or office today.


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Joseph

17 years of experience
38 reviews
Joseph
17 years of experience
Kia Rio - Cooling System Flush - Fort Lauderdale, Florida
Book Joseph Williams for your next auto repair! You'll be glad that you did. Joe is a very honest, reliable, professional, knowledgeable, and nice mechanic. He goes above and beyond to get the job done right. The best in the business. Give him a try!! Thank you.
Ford Explorer Sport Trac - Cooling System Flush - Dania, Florida
Joseph was running a bit late due to traffic but contacted me by text to let me know. He performed the work in good time and gave me solid recommendations.

Nicholas

11 years of experience
444 reviews
Nicholas
11 years of experience
Chevrolet Camaro - Cooling System Flush - Raleigh, North Carolina
Nicholas really does excellent work. Arrived early. He is honest and upfront. Very competent and knowledgeable regarding auto mechanics. He explained everything thoroughly in detail (before, during, and even after the service). I would highly recommend him.
Chrysler Aspen - Cooling System Flush - Apex, North Carolina
Excellent service, as usual. Have used Nicholas in the past and he does not disappoint. Arrived early and was ready to work. Diagnosed the problem and took care of it in a very professional manner. Saved me both time and money. Very honest and up-front. Could not be more satisfied. Highly recommend. Will continue to use in the future.

Joel

30 years of experience
66 reviews
Joel
30 years of experience
Infiniti G37 - Cooling System Flush - Phoenix, Arizona
Joel was very professional and demonstrated technical expertise that was very impressive. He addressed all of my schedule services and more. Thanks Joel!

Andrian

32 years of experience
184 reviews
Andrian
32 years of experience
Hyundai Genesis Coupe - Cooling System Flush - Fort Lauderdale, Florida
Adrian was incredibly helpful, skilled, and professional. I will absolutely use YourMechanic again and recommend it to others.

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