You pull into a gas station after your car flashes a ‘Low Coolant’ warning, and ask for coolant, but the helper casually hands you a bottle of antifreeze instead.
That may make you wonder, “Is coolant and antifreeze the same thing?”
Quick answer: No.
Coolant is diluted antifreeze (with water) that regulates engine temperatures.
To help you out, we’ll explain the difference between coolant and antifreeze in depth. We’ll also brief you on when and how to top up or flush the fluid.
This Article Contains:
- What Is a Coolant and How Is It Different from Antifreeze?
- When Should You Change or Top Up Your Car’s Coolant?
- Why Is It Important to Maintain Correct Coolant Levels?
- How to Perform a Coolant Flush or Top-up: A General Know-How
- How to Choose the Right Coolant for Your Vehicle
- 3 FAQs about Car Coolants
What Is a Coolant and How Is It Different from Antifreeze?
Engine coolant is a mixture of antifreeze and water. It plays a crucial role in your vehicle’s cooling system by regulating engine temperatures for maximum performance and efficiency.
On the other hand, antifreeze — typically made from ethylene glycol or propylene glycol — doesn’t effectively transfer heat on its own. However, it has a high boiling point and a low freezing point, which helps coolant from overheating in summer or freezing in cold temperatures.
When mixed with water (a good heat conductor), the resultant liquid becomes a good heat conductor, along with a high boiling point and a low freezing point. This ensures the coolant doesn’t freeze in cold weather or heat up in summer.
Beyond regulating engine temperatures, antifreeze also has corrosion inhibitors that protect the engine, boost performance, and prevent long-term damage.
Based on these additives, coolants can be classified into different types, such as:
- IAT (Inorganic Additive Technology): This conventional ethylene glycol-based coolant uses chemicals, such as silicates and phosphates, to prevent corrosion. It’s usually used in older vehicles.
- OAT (Organic Acid Technology): This long-life ethylene glycol-based coolant uses organic acids for corrosion protection. It’s free of harmful chemicals, so it’s popularly used in modern vehicles.
- HOAT (Hybrid OAT): This ethylene glycol- or propylene glycol-based coolant combines organic and inorganic acids to inhibit corrosion. It’s used in all types of vehicles.
NOTE: Propylene glycol is used as antifreeze in vehicles where there’s a higher potential of human or environmental exposure because it’s less toxic than ethylene glycol. However, propylene glycol has a higher freezing point and lower boiling point, making it less efficient than ethylene glycol.
Now, let’s discuss when to change engine coolant, because even the best coolant can go bad.
When Should You Change or Top Up Your Car’s Coolant?
A coolant flush can help remove rust, dirt, and other debris that build up in the cooling system due to corrosion and old coolant. If not, these particles can accumulate and damage your engine over time.
Here’s a general guideline for changing different coolant types:
- IAT coolant: Every 2 years or 30,000 miles
- HOAT coolant: Every 5 years or 100,000 miles
- OAT coolant: Every 10 years or 150,000 miles
But perform a coolant flush earlier if you notice certain symptoms:
- Rust or sediments in the coolant reservoir
- Hard or brittle radiator hoses in the cooling system
- Dirty, sludgy, or discolored antifreeze water mixture
Likewise, top up your engine coolant regularly, as it can evaporate due to heat or leak through cracks and holes.
Here’s how your car will signal you when it’s low on coolant:
- Active engine coolant warning light on the dashboard
- Illuminated Check Engine Light
- Steam coming from under the hood
- The temperature gauge shows high engine temperatures
- Cabin heater doesn’t work properly
- Visible coolant leaks from the cooling system
Now you must be wondering: why top up the fluid at all?
Keep reading to find out!
Why Is It Important to Maintain Correct Coolant Levels?
Ensuring your car has sufficient levels of clean engine coolant can help:
- Improve engine performance: Removing contaminants and debris (caused by corrosion or residue buildup) from the cooling system allows the coolant to flow freely. This helps the engine run efficiently.
- Restore cooling efficiency: Regular flushes clear blockages that restrict coolant flow, making the cooling system more efficient.
- Increase the engine’s lifespan: Eliminating corrosion and scale buildup helps protect vital components like the radiator, thermostat, and cylinder head, ultimately increasing the vehicle’s lifespan.
- Lubricate the water pump and prevent leaks: Modern coolants contain lubricants and active additives that keep the water pump running smoothly and seal small leaks.
That brings us to another question:
How to Perform a Coolant Flush or Top-up: A General Know-How
A coolant flush can be time-consuming and tedious. It involves complete draining and refilling of the cooling system to remove old fluid and built-up contaminants. For your safety, it’s a job best left to a mechanic.
Here’s how they’ll carry out a coolant flush or top up the fluid:
Step 1: Drain the Old Engine Coolant
They’ll place a tray under the radiator drain plug and remove the plug to collect the coolant out of the radiator.
Step 2: Flush with Distilled Water
The mechanic will fill the reservoir with distilled water, as using anything else can cause mineral buildup. They’ll then run the engine for 10-15 minutes with the heater on to get the coolant into the heater core. Once done, they’ll let the engine cool completely.
Next, they’ll drain the water through the radiator, just like they did with the old coolant, and repeat the process until the drained water runs clear.
Step 3: Refill or Top up the Coolant
Finally, the mechanic will fill the reservoir with coolant until it reaches just below the “MAX” level. Then, using a bleeder valve, they’ll remove air pockets from the cooling system.
NOTE: If the coolant reservoir is missing or the system requires direct radiator access, the mechanic will access the radiator cap — but only after ensuring that the engine heat has dissipated completely. Then, they’ll repeat all the above steps and pour the coolant till it reaches the lip of the pipe’s opening. Before closing the radiator cap, they’ll remove all air pockets.
But here’s the thing:
You can’t just add any antifreeze water mixture to your car. So, before you top off or replace your coolant, there are some key aspects you should consider.
How to Choose the Right Coolant for Your Vehicle
While selecting the right coolant for your vehicle, consider these factors:
- Climate: If you live in cold weather, choose an engine coolant with a low freezing point to prevent freezing. Likewise, in the summer heat, choose a coolant with a high boiling point to work efficiently as the engine heats up due to high outside temperatures.
- Engine type: Some engines require a specific type of coolant, and using the wrong one can damage the engine. For example, engines of older vehicles are most compatible with ethylene glycol-based IAT coolant due to its corrosion inhibitors. So, before you add or change your coolant, ensure it’s compatible with your engine.
- Budget: Some coolants, like ethylene glycol-based OAT, are more expensive than ethylene glycol-based IAT coolants.
- Driving habits: Coolants have different properties, making some more suitable for specific driving habits. For example, OAT coolant has organic corrosion inhibitors that degrade more slowly than inorganic corrosion inhibitors, offering a longer lifespan and requiring less frequent replacements.
NOTE: If you still can’t choose, go for a universal coolant (typically based on ethylene glycol), as it’s compatible with different types of engines. However, be wary of using it in an older car as it may damage the brass or copper components.
Have other doubts?
Let’s learn a thing or two more about engine coolants.
3 FAQs about Car Coolants
Here are answers to the most commonly asked questions about coolants:
1. How Does the Engine Coolant Work?
When the engine heats up, the water pump (part of the cooling system) pushes the coolant through the engine block to absorb the heat produced during combustion. The coolant then flows to the radiator, where it releases heat into the atmosphere. This cycle repeats as the engine continues to run and heat up.
NOTE: When the vehicle’s heater is on, some of the hot coolant from the engine flows into the heater core to heat the cabin.
2. How Much Will a Coolant Flush Cost?
The amount you may pay for a coolant flush depends on your vehicle’s make, engine size, labor costs, and coolant type. The cost typically ranges from $140 to $250, which includes:
- New coolant: $10 to $40
- Additives: $15 to $20
- Radiator cleaner: $15 to $20
- Labor cost: $100 to $170
3. Can You Top Up the Coolant Reservoir with Water?
Yes, but only in emergencies. If you don’t have the proper coolant, you can temporarily top it off with distilled water. Avoid tap water, as it can cause mineral buildup in the cooling system.
However, remember that plain water isn’t as effective as a coolant in regulating engine temperatures. Over time, driving this way can lead to overheating and engine damage.
Restore Your Cooling System with AutoNation Mobile Service
Driving with contaminated or low coolant can damage essential vehicle systems. The more you delay a flush or top-up, the higher the repair costs will be.
Don’t want to risk driving to the repair shop with low coolant levels?
Contact AutoNation Mobile Service to perform routine maintenance services, like a coolant flush or top-up, at your convenience, wherever you are. We’re also available seven days a week and offer a 12-month, 12,000-mile repair warranty.
Contact us now to keep your engine temperatures and repair expenses in check.