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Checking the coolant level

2025 Hyundai Tucson engine coolant reservoir image. A black arrow points downward to the coolant reservoir tank located in the engine compartment. Explains the location of the reservoir for checking the coolant level.

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Check the condition and connections of all cooling system hoses and heater hoses. Replace any swollen or deteriorated hoses.

The coolant level should be filled between the MAX and the MIN marks on the side of the coolant reservoir when the engine is cool.

If the coolant level is low, add enough distilled (deionized) water to bring the level to the MAX mark, but do not overfill. If frequent additions are required, we recommend that you see an authorized HYUNDAI dealer for a cooling system inspection.

2025 Hyundai Tucson Radiator Hot Warning icon. It depicts a radiator tank with wavy lines representing coolant and upward arrows indicating heat. A hand reaching for the cap is crossed out with an X mark. This warns against opening the radiator cap when the engine is hot to prevent injury from escaping steam and hot coolant.

Never remove the engine coolant cap or the drain plug while the engine and radiator are hot. Hot coolant and steam may blow out under pressure, causing serious injury.

Turn the vehicle off and wait until the engine cools down. Use extreme care when removing the engine coolant cap. Wrap a thick towel around it, and turn it counterclockwise slowly to the first stop. Step back while the pressure is released from the cooling system. When you are sure all the pressure has been released, press down on the cap, using a thick towel, and continue turning counterclockwise to remove it.

2025 Hyundai Tucson cooling fan warning label image. The label displays a warning triangle and manual symbol, a 'do not touch' hand symbol inside a prohibition circle, and an illustration of a hand near a rotating fan blade. It warns to keep hands away from the cooling fan to prevent serious injury.

The electric motor for the cooling fan may continue to operate or start up when the engine is not running and can cause serious injury. Keep hands, clothing and tools away from the rotating fan blades of the cooling fan.

Always turn off the vehicle unless the vehicle has to be inspected with the engine on. Be cautious as the cooling fan may operate if the negative (-) battery terminal is not disconnected.

Make sure the coolant cap is properly closed after refilling coolant. Otherwise the engine could be overheated while driving.

Engine compartment front view
2025 Hyundai Tucson engine coolant cap alignment image. The left shows the cap with the label aligned horizontally straight. The right shows the cap rotated with a prohibition symbol overlaid. Explains how to check if the coolant cap is properly closed by ensuring the label is straight.

2C_CheckCoolantCapLocked

  1. Check if the coolant cap label is straight in front.

    2025 Hyundai Tucson coolant cap alignment image. The grey cap displays a warning label with steam and hand icons on top. It illustrates the function of checking if the label is straight in front to ensure the cap is securely locked.

    2C_CheckCoolantCapLocked_2

  2. Make sure that the tiny protrusions inside the coolant cap are securely interlocked.

The coolant level is influenced by the engine temperature. Before checking or refilling the coolant, turn the engine off.

Recommended coolant

  • When adding coolant, use only deionized water, distilled water or soft water for your vehicle and never mix hard water in the coolant filled at the factory.

  • An incorrect coolant mixture can result in severe malfunction or engine damage.

  • The engine in your vehicle has aluminum engine parts and must be protected by an phosphate-based ethylene glycol coolant to prevent corrosion and freezing.

  • Do not use alcohol or methanol coolant or mix them with the specified coolant.

  • Do not use a solution that contains more than 60% antifreeze or less than 35% antifreeze, which would reduce the effectiveness of the solution.

For mixing percentage, refer to the following table:

Ambient Temperature

Mixture Percentage (volume)

Antifreeze

Water

-15°C (5°F)

35

65

-25°C (-13°F)

40

60

-35°C (-31°F)

50

50

-45°C (-49°F)

60

40

If in doubt about the mix ratio, a 50% water and 50% antifreeze mix is the easiest to mix together as it will be the same quantity of each. It is suitable to use for most temperature ranges of -35°C (-31°F) and higher.