Engine coolant is vital to the continued healthy performance of your vehicle, so make sure you understand how it works.
You have probably heard of coolant or car antifreeze and that it goes into your car's radiator. Antifreeze and coolant are often used interchangeably, but is coolant the same as antifreeze? For the most part, the liquid in your car radiator, called coolant, is actually a blend of antifreeze and water. The water pump first circulates it around the engine to absorb heat, then through the radiator to dissipate the heat into the wind stream before starting the process again to keep your engine at safe operating temperature. All cars with an internal combustion engine have an engine-cooling system - even hybrids.
You must add the correct type of car antifreeze to your radiator coolant, and in the correct concentration, to properly protect your engine. If there is no coolant in the car, the engine will overheat and if you don't stop in time, a gasket might blow and the coolant and oil might mix; water in oil can ruin an engine. Driving on might also cause the engine to seize, wrecking it. Additional components may become damaged due to the heat and there could even be a fire hazard. Always keep an eye on the warning lights on your dashboard to pre-empt this, and read up on common car problems like this here.
Antifreeze is a specially formulated liquid usually containing glycol that lowers the freezing point of your engine coolant and increases its boiling point. It protects your engine in three ways. An increased boiling point inhibits bubbles that can push water out of the system. A lower freezing point prevents the expanding ice due to water freezing from damaging the engine cooling system. Anti-corrosion and anti-cavitation properties protect the cooling system's components. Engine designers determine the type of antifreeze concentrate that should be used and the ratio of the mixture.
There are typically four antifreeze types, each with a different color and chemical composition:
These colors are not cast in stone, so always read the label. Antifreeze might be other colors too, like blue, purple, or turquoise.
First, get the right radiator fluid, meaning you have to find the right antifreeze and mix it with water in the right ratio - usually 50/50 - before adding it. Alternatively, buy the correct premixed coolant. Don't use old coolant unless you have a refractometer to check its condition; this is a tester that determines the glycol-to-water ratio.
Don't just buy some 'universal' antifreeze and hope for the best. Buy the right stuff and don't take shortcuts with this important fluid - its price will rarely be more than $10 to $20 per gallon at most. Follow the correct disposal rules for old coolant, too, because antifreeze is toxic. There are a few non-toxic variants, but they usually cost more. Enquire at your local recycling center if you are unsure.
For a full discussion on how to check the antifreeze/coolant level, be sure to read about important maintenance to schedule here, and follow these steps:
If you need to do this frequently, there could be a leak that must be fixed urgently. Removing the cap on a hot engine can eject coolant and severely burn you, so never attempt it.
Running out of coolant due to a leak can severely damage or ruin your engine. Repairing or replacing it can be so expensive that it may be more cost-effective to just buy a new vehicle. Coolant is critical to keeping your engine running at optimal temperature and the car's cooling system should never be neglected. Have yours checked for leaks frequently and replace the coolant as required. Remember, EVs also use a coolant to cool their batteries and even the best electric cars need to have this coolant replaced periodically.
Antifreeze can be seen as a constituent of coolant, usually blended with water in a 50:50 ratio; coolant is necessary to transfer heat and prevent damage caused by freezing, and boiling over Coolant is added to the cooling system, which you can find by looking for a brightly colored cap with a picture or text on it saying that it's the coolant cap.
This will usually be indicated in your owner's manual. Luxury cars and SUVs or trucks with large, powerful engines may take several gallons of coolant. For example, the 3.0-liter Duramax diesel engine in a Chevrolet Silverado takes 20.2 quarts of coolant and a Ford F-150 3.5-liter EcoBoost Hybrid takes 21.4 quarts. Besides preparing the correct blend to fill an empty cooling system, you might need the help of an expert to bleed it, otherwise, air may remain trapped in the system, degrading the cooling system's performance.
The coolant could be leaking out, resulting in a puddle on the floor in the morning. If a gasket has blown, water can leak into the pistons and be ejected as steam through the exhaust without a trace. A blown gasket could also lead to water mixing with oil, resulting in a milky appearance of the latter. Never ignore a water leak and always have it attended to.
It will be indicated in your owner's manual. Alternatively, you can phone the workshop of your authorized dealership and ask them. Most car-parts shops also keep a list of the correct antifreeze if you can tell them exactly what year and model car you drive.
Yes, you can top up with plain water - once the engine has cooled down completely - but once back at home base, drain and flush the system and replace the coolant with the correct blend immediately.