How Often Should I Change Engine Coolant?

When is the right time to change your engine coolant? For some vehicles, you’re advised to change the coolant every 30,000 miles. For others, changing it isn’t even on the maintenance schedule.

For example, Hyundai says the coolant in the engine (what many refer to as “antifreeze”) in most of its models should be replaced after the first 60,000 miles, then every 30,000 miles after that. The interval is every 30,000 miles on some Mercedes-Benz models with some engines, but on others it’s 120,000 miles or 12 years. On still other Mercedes, it’s 150,000 miles or 15 years.

Some manufacturers recommend you drain and flush the engine’s cooling system and change the coolant more often on vehicles subjected to “severe service,” such as frequent towing, which can generate more heat. The schedule for many Chevrolets, though, is a change at 150,000 miles regardless of how the vehicle is driven.

Many service shops, though — including some at dealerships that sell cars with “lifetime” coolant — say you should do a coolant change more often than the maintenance schedule recommends, such as every 30,000 or 50,000 miles.

Here’s why: Most vehicles use long-life engine coolant (usually a 50/50 mixture of antifreeze and water) in the radiator that for several years will provide protection against boiling in hot weather and freezing in cold temperatures, with little or no maintenance. Modern vehicles also have longer intervals between fluid changes of all types partly because environmental regulators have pressured automakers to reduce the amount of old coolant, as well as other waste fluids, that must be disposed of or recycled.

Coolant can deteriorate over time and should be tested to see if it’s still good, as it can be hard to tell just by appearances. Even if the coolant reservoir shows sufficient coolant level and testing shows the cooling and antifreeze protection are still adequate, a coolant drain and antifreeze flush may be needed.

The coolant can become more acidic over time and lose its rust-inhibiting properties, causing corrosion. Corrosion can damage the radiator, water pump, thermostat, radiator cap, hoses and other parts of the cooling system, as well as to the vehicle heater system. And that can cause a car engine to overheat.

Thus, the coolant in any vehicle with more than about 50,000 miles should be tested periodically. That’s to look for signs of rust, leaks and to make sure it has sufficient cooling and overheating protection, even if the cooling system seems to be working properly and the reservoir is full. The cooling system can be checked with test strips that measure acidity, and with a hydrometer that measures freezing and boiling protection.

If the corrosion inhibitors have deteriorated, the antifreeze coolant should be changed. The cooling system might also need flushing to remove contaminants no matter what the maintenance schedule calls for or how many miles are on the odometer. On the other hand, if testing shows the coolant is still doing its job protecting from overheating and not allowing corrosion, changing it more often than what the manufacturer recommends could be a waste of money.

Antifreeze Safety Precautions

When you work with antifreeze, there are some safety precautions you should always follow. Here are a few to consider.

• Maintain your vehicle while parked on a flat, even surface. 
• Use the parking brake to keep the vehicle from rolling during service. Wheel chocks can also help to keep it stable.
• Add coolant with the engine turned off. 
• The engine should be completely cool before you open the reservoir cap. If the engine is warm to the touch, it’s best to wait longer. 
• Never wear loose clothing while servicing your vehicle. If you have loose sleeves, roll them up before getting under the hood. 
• Wear protective equipment. It’s best to have safety glasses and gloves on. You may also choose to wear dirty clothes or an apron to protect against coolant stains.
• Never ingest antifreeze. It is extremely toxic. If you accidentally ingest coolant, you must call 000
• Keep antifreeze away from children and animals. Store the coolant in a safe location. 

How to Add Coolant to Your Vehicle

To add antifreeze to your car, you must first gather all of your supplies, cool off the engine, and locate the coolant reservoir. Once you check the antifreeze levels, you can take off the cap and fill it appropriately. Plus, you want to inspect the system to ensure there are no leaks or problems. 

Here is a more detailed list of how to add antifreeze to your vehicle:

1. Gather Equipment

Your vehicle requires a 50/50 combination of water and antifreeze, but some store-bought formulas are already mixed. Make sure you read the label carefully. It’s also important that you opt for the appropriate color based on what the manufacturer specifies. You can find antifreeze that’s colored blue, green, red, pink, yellow or orange. You can often find the manufacturer specs you need in the owner’s manual.

Aside from choosing the right coolant, you also want to have all of your supplies and tools handy for an easier job. After all, it only becomes more complicated if you need to walk away while filling the antifreeze to gather more supplies. 

2. Cool Car Engine

It’s important to turn off the car engine and give it time to cool down. Antifreeze shouldn’t be added while the engine is hot. Most importantly, you don’t want to get burned by touching a hot engine. Plus, the reservoir cap can be hot, holding back liquid that reaches boiling temperatures.

Another reason to wait is because any sudden temperature change can lead to cracks in the engine. If you rapidly change the temperature from hot to cold, you could face hefty engine repair bills. 

Even if the engine has overheated and you need to add more antifreeze, it’s best to wait until the motor is cooler. Give it at least 15 minutes before you attempt to open the coolant cap. 

3. Find Engine Coolant Reservoir

It’s not hard to find the coolant reservoir. Most brands use a colored cap to make it easier. Not only might it be painted yellow, but it should also have a warning on it, telling you not to open it while the engine is hot.

If you can’t find the plastic cap, look in your owner’s manual. This booklet outlines where the vital parts are located, including the coolant cap. 

4. Check Antifreeze Levels

You should be able to check the antifreeze level without taking the cap off. If you look at the reservoir, you will see the minimum and maximum lines printed on it.

With the bright-colored coolant inside the translucent container, it’s easy to gauge. The coolant level must be between these two markers. The levels will change depending on whether the engine is hot or cold, but keeping it between these lines ensures proper operation at all times. 

5. Take Off Cap

If you need to top off the system, you have no choice but to remove the reservoir cap. It should screw off, but you should use caution.

Any damage to the cap can lead to cooling system issues. Use caution, so it doesn’t become damaged in the process. 

6. Add the Antifreeze

If the antifreeze needs to be diluted, now is the time to do so. Once you have the appropriate mixture, it’s time to add some into the system.

With the use of a funnel, you can pour the appropriate amount of antifreeze into the reservoir. Once it reaches between the two indicator lines, you will stop pouring. 

7. Check System

Fasten the cap back in place and run the car engine. You want to perform a quick inspection of the cooling system, looking for any leaks or issues.

If you notice a leak, you must deal with the problem promptly or the engine could overheat. Otherwise, you are ready to hit the road. If the coolant system was almost empty before, you may need to bleed the cooling system.