How do I check and refill the engine coolant?

Learn how to properly check and refill the engine coolant in your Ford vehicle to prevent overheating and extend its lifespan.

Safety Precautions Before Checking and Refilling Coolant

Note: The engine cooling system operates under high pressure. Extremely hot steam and liquid can erupt forcefully and cause severe personal injury. Please follow these instructions for your safety:

  • Do not remove the coolant reservoir cap while the engine is running or when the cooling system is hot.
  • Wait at least 10 minutes for the cooling system to cool down before you perform any action.
  • Cover the coolant reservoir cap with a thick cloth before unscrewing it, and slowly turn it to safely vent any remaining pressure.
  • Avoid letting coolant contact your skin or eyes. If contact occurs, immediately flush the affected area with plenty of clean water and seek medical attention.
  • Do not put engine coolant in the windshield washer reservoir. If sprayed on the windshield, engine coolant can make it extremely difficult to see.

How to Check Coolant Level and Concentration

You should check the coolant level when the engine is completely cold, adhering to the following guidelines:

  • Correct Coolant Level: Ensure that the coolant level in the coolant reservoir is between the MIN and MAX marks.
  • Expansion When Hot: When the engine is hot, the coolant expands, and the level may temporarily rise above the MAX mark. This is normal.
  • Coolant Concentration: Maintain the coolant concentration within 48% to 50% (which equates to a freeze point between -34 °C and -37 °C). We recommend checking the concentration using a refractometer. Do not use hydrometers or coolant test strips.

How to Properly Refill Engine Coolant

If the coolant level is at or below the MIN mark, you must immediately add prediluted engine coolant meeting Ford specifications, following these steps:

  1. Unscrew the coolant reservoir cap slowly to release any remaining pressure.
  2. Add prediluted engine coolant meeting Ford specifications into the reservoir. Do not add coolant past the MAX mark.
  3. Reinstall the coolant reservoir cap by turning it clockwise until it is fully tight.
  4. Check the coolant level in the reservoir again the next few times you drive the vehicle.

Note:

  • Do not mix different colors or types of coolant in your vehicle. Do not use stop leak pellets, cooling system sealants, or non-specified additives, as they can cause damage to the engine or cooling system. Resulting component damage may not be covered by the vehicle Warranty.
  • If prediluted coolant is not available, you can use approved concentrated coolant diluted to a 50/50 ratio with distilled or deionized water. Do not use tap water or undistilled water, as it can cause scale deposits, corrosion, and clogging in the cooling system.
  • If you need to add more than 1L of coolant per month, please have your vehicle inspected at a Ford service center as soon as possible.
  • In an emergency, you can add a large amount of clean water to reach a service center. However, do not use it for the long term, and never use alcohol, methanol, or salt water as a substitute for engine coolant.

Managing Engine Overheating

Under heavy vehicle usage, such as towing uphill in hot weather, the engine temperature may rise, causing the temperature gauge to move into the red zone and a warning light or message to appear on the information display.

Note: Do not continue driving if the coolant warning light illuminates. The engine will reduce its power and speed to protect itself, and the engine may shut down without warning. This could cause a loss of vehicle control, resulting in serious personal injury or death.

If the temperature gauge moves into the red zone, follow these steps:

  1. Pull off the road safely as soon as possible, fully apply the parking brake, and shift into park (P) or neutral (N).
  2. Allow the engine to idle until the temperature gauge needle returns to the normal range. If the temperature does not drop after several minutes, turn off the engine and let it cool down to check the coolant level.
  3. Check the coolant level. If it is at or below the MIN mark, immediately add prediluted engine coolant.
  4. Restart the engine in an open, well-ventilated, and safe area if the coolant level is normal, then continue driving.

Changing the Engine Coolant

Changing the engine coolant at the specified intervals is essential to maintain optimal engine performance. Please contact an authorized Ford Dealer to have the coolant changed according to the scheduled maintenance guide.

* Information referenced from the 2026 Owner's Manual.

** The specifications, procedures, methods, and warnings regarding the engine cooling system presented in this article are provided for general informational and convenience purposes only. Actual details may vary depending on the vehicle model, model year, optional equipment, and country of sale. Ford Thailand reserves the right to change details and specifications without prior notice. The information in this article does not constitute a contractual warranty and cannot be used as a legal reference or for any claims. Please verify the correct and most accurate information for your specific vehicle in your actual Owner's Manual, or contact an authorized Ford Dealer for further information.