2018 Honda Civic Coolant Capacity & Type

The 2018 Honda Civic's cooling system holds approximately 6.1 to 6.3 quarts (5.8 to 6.0 Liters) of coolant, depending on the engine and transmission combination.

Quick Answer

• Total Cooling System Capacity: 6.1 - 6.3 quarts (5.8 - 6.0 Liters)
• OEM Coolant Spec: Honda Type 2 Coolant (Blue, Phosphated HOAT, Honda P/N 08C02-A011L-01 for concentrate or 08C02-A011RM-01 for pre-mix)
• Mix Ratio: 50/50 Pre-mix or 50/50 concentrate with distilled water

Capacity by Engine Option

Note: These capacities are for a complete drain and fill, including the radiator, engine, and heater core.

Flush Interval

For a 2018 Honda Civic, Honda recommends the following coolant flush intervals:

• Normal Duty: Initial replacement at 10 years or 120,000 miles, then every 5 years or 60,000 miles thereafter.
• Severe Duty: If your driving conditions fall under "severe" (e.g., frequent towing, extreme temperatures, dusty conditions, extensive idling), it's wise to consider changing the coolant more frequently, possibly every 3-5 years or 30,000-50,000 miles.

Always refer to your owner's manual for the most accurate and up-to-date maintenance schedule for your specific vehicle.

How to Refill & Bleed

Properly refilling and bleeding the cooling system is crucial to prevent air pockets, which can lead to overheating. Here's a general procedure for the 2018 Honda Civic:

1. Drain the System: With the engine cool, place a drain pan under the radiator. Open the radiator drain plug (usually on the bottom of the radiator). Remove the radiator cap to speed up draining. Some models may have an engine block drain plug as well. Consult your service manual.
2. Close Drain Plugs: Once drained, close the radiator drain plug and any engine block drain plugs securely.
3. Refill with New Coolant: Slowly fill the radiator with new Honda Type 2 coolant (50/50 pre-mix or concentrate mixed with distilled water to a 50/50 ratio) until it reaches the base of the filler neck. Fill the reservoir to the "MAX" line.
4. Burp the System: Leave the radiator cap off. Start the engine and let it run with the heater on full blast (hot) and the fan on low. This helps open the thermostat and circulate coolant through the heater core. Squeeze the upper and lower radiator hoses several times to help dislodge air bubbles.
5. Monitor Coolant Level: As the engine warms up, the coolant level in the radiator may drop. Continuously top it off to the base of the filler neck. Look for air bubbles escaping from the radiator filler neck. Continue this process until no more bubbles appear.
6. Install Radiator Cap: Once the engine reaches operating temperature and no more bubbles are visible, install the radiator cap.
7. Final Check: Drive the vehicle and monitor the temperature gauge. After the engine cools down completely, recheck the coolant level in the reservoir and top off if necessary.

Important Note: The 2018 Honda Civic typically does not have a dedicated bleed screw. The method described above, involving a prolonged burping process with the cap off, is generally sufficient. A vacuum-fill tool can also be used for a more thorough and quicker air removal, especially in systems prone to stubborn air pockets.

Common Cooling System Issues (2016-2021 Honda Civic Generation)

While generally reliable, the 10th generation Honda Civic (which includes the 2018 model) can experience some cooling system issues:

• Water Pump Leaks: Some owners have reported premature water pump leaks. Keep an eye out for coolant puddles under the front of the car or a sweet smell.
• Thermostat Issues: A faulty thermostat can cause the engine to run too hot or too cold. Symptoms include an erratic temperature gauge or the engine taking a long time to warm up.
• Radiator Fan Motor Failure: The cooling fan is essential for maintaining proper temperature, especially in stop-and-go traffic or at idle. A malfunctioning fan can lead to overheating. Listen for unusual noises from the fan or check if it's not engaging when the engine gets hot.
• Cracked Radiator or Hoses: Over time, plastic radiator tanks and rubber hoses can degrade and develop cracks or leaks. Regularly inspect these components for any signs of wear or leakage.
• Coolant Reservoir Leaks: The plastic coolant overflow reservoir can sometimes develop cracks, leading to slow coolant loss.

Regular inspection and adherence to the recommended maintenance schedule can help prevent these issues and ensure the longevity of your Civic's cooling system.

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