How to Tell What My Radiator Coolant Capacity Is

Knowing what your radiator coolant capacity is can mean the difference between keeping your engine at a safe operating temperature and overheating. Having information on your coolant capacity also helps when it comes to adding the proper mixture of water and antifreeze. The process for finding out how much coolant your radiator can hold is relatively simple.

Things You'll Need:

• 1 quart container
• Ratchet and socket
• Distilled water
• Coolant

1. Place a catch pan underneath the radiator

Place a catch pan underneath the radiator and remove the radiator’s drain plug with a ratchet and socket. Allow the fluid to drain out of the radiator and replace the drain plug when finished. Drain or siphon all coolant from the overflow reservoir. Dispose of the old coolant in an environmentally-friendly (and legal) manner.

2. Open the cap on the radiator

Open the cap on the radiator. Fill several 1 qt. containers with distilled water. Have a pen and pad ready to keep track of number of quarts added into the radiator.

3. Fill the radiator with water 1 qt. at a time

Fill the radiator with water 1 qt. at a time. Record each quart added into the radiator. Most radiator capacities vary from 11 qts. to 28 qts. for most vehicles. Fill the radiator until the water level reaches the expansion tank piping. When finished, tally up the result.

4. Drain the water from the radiator

Drain the water from the radiator. Fill the radiator with the appropriate mix of coolant and water. Remove the catch pan and check for leaks. Close the top on the radiator and dispose of the used water. Refill the overflow reservoir to the correct level with coolant.

Tips and Warnings

Most automotive owner’s manuals will have the coolant capacity listed along with other specifications. Attempt the steps above only if you cannot find your owner’s manual or if the radiator does not come with an instructional manual that lists the coolant capacity.

It is recommended that you record the coolant capacity for future reference in a safe, easily accessible area.

Never attempt to remove a hot radiator cap. Hot coolant can spray from the radiator, causing burns and severe injury.

Video showing how to check your car's coolant level:

Helpful comments on this video:

• One thing I'd like to point out is that the overflow tank is not pressurized as he's saying in the video, so you can open it when the car is hot. However, do not open the pressurized radiator cap when hot. Some cars do not have an overflow and the only cap to refill coolant is the pressurized radiator cap...again, not to be opened when hot.
• The indicators on the reservoir only apply when the engine is not hot. Don't add coolant unless the engine is cold and the level is at or below the "LOW" level on the reservoir.