How to Test Antifreeze Level

by Contributor

Routine car maintenance is important to extend the life of your vehicle. Radiators need a certain level of antifreeze to lower their freezing point and raise their boiling point and thus protect the engine block from damage. There are a few simple steps involved in testing your antifreeze levels; and it's a good practice to do it twice a year. Read on to learn more.

Allow your engine to cool down for at least 30 minutes before checking your antifreeze level. Removing caps on radiators and coolant reservoirs can be dangerous because some of the systems are under pressure when they're hot and may blow boiling liquid out on you if you open them before letting the engine cool down.

Begin by looking for the coolant reservoir, which is where you add antifreeze, and is found on most vehicles manufactured after the 1970s. This tank expands when the engine heats up, allowing hot coolant to enter the tank and contracts when the engine cools down, drawing the coolant back into the radiator. As long as the radiator cap is sealed, this process will continue without losing any coolant. This reservoir is usually a transparent white color with the words "full" and "low" visible on the side. If you have an older vehicle without the coolant reservoir, check the fluid by removing the radiator cap.

Remove the cap on the coolant reservoir and look for a transparent liquid, which is usually pink, blue or green depending on the brand of antifreeze it has. If it's brown or rusty, have the radiator flushed out by a car maintenance specialist, and if there is oil in the reservoir, it may indicate a blown head gasket, which also needs repair. If your antifreeze is clear, proceed to the next step of testing the level.

Check the level of the coolant by looking at the marks on the side of the tank. The two marks indicate the levels of the coolant when the engine is hot, which is marked "full," and when it's cold, which is marked "low." If it's between the low and full mark, it's fine. If it's a little low add water to get it back to the proper level, but if it's more than a quart low, you'll need to add more antifreeze and then test the freeze point to see if it has the proper level needed to protect your engine.

Purchase an antifreeze tester, available at automotive parts stores. It's easy to use, and the instructions are included on the packaging. This will tell you whether you have the right level of antifreeze.

Replace the cap securely when you've finished. Check the hoses going to the radiator and coolant reservoir to make sure there aren't any cracks or leaks. Routine car maintenance gives you an opportunity to catch problems before they cause serious damage to your engine.


  • close Antifreeze is very toxic to animals. They love to drink it so be sure to clean up any spills.

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