Adding coolant to your car is a simple task, yet, it makes all the difference in the world for safeguarding your engine and preventing costly repairs down the road.
From protecting against freezing and overheating to keeping corrosion at bay, this vital fluid plays a few different roles. But the actual process of refilling or replacing it can lead to uncertainty. For example, does the car need to be running when adding coolant?
This is a common question our customer service team gets asked here at Jennychem, as we are a leading provider of coolants in the UK. The answer is no - in fact, adding coolant to a running vehicle is downright dangerous.
We’ll explain why below along with how this misconception came about in the first place. More importantly, though, you’ll learn how to actually add coolant to your car so you can feel confident handling this routine vehicle maintenance task. Let’s start with the basics, though.
So, why do I need to put antifreeze in my car? This is perhaps the most essential fluid for safe, reliable vehicle operation - except for gasoline, of course. But before we get into the role it plays, let’s make on thing clear: is antifreeze the same as coolant? Not at all.
Antifreeze refers to the raw fluid itself, whereas coolant is what you end up with after mixing antifreeze with distilled water. A simple way to look at it is antifreeze is the product you purchase, while coolant is what actually circulates in your vehicle.
Whatever you call it, the fluid itself keeps your vehicle’s cooling system safe and effective year-round. It lowers the freezing point of water so that the harsh winter chill of the UK can’t cause freezing and expanding, which would otherwise crack the engine block or radiator.
Meanwhile, it raises the boiling point of water to prevent overheating during stop-and-go traffic on hot summer days, while towing heavy loads, or embarking on long road trips.
Coolant works by absorbing heat and transferring it to the radiator, where it is dissipated. But temperature regulation is just half of its purpose. Other antifreeze ingredients provide advanced protection from corrosion as well.
This safeguards sensitive components like the radiator, water pump, and hoses from rust and scale buildup. These contaminants could degrade the cooling system’s efficiency and lead to leaks or blockages, so keeping them at bay is important.
You can’t overlook the importance of coolant, no matter how or where you drive. Like all vehicle fluids, it needs to be regularly checked and topped off - or in some cases, replaced altogether.
This begs the question, how long does coolant last? In optimal conditions, you can go 2-5 years (or 48,000-100,000 km), before replacing it. When the time eventually comes, does the car need to be running when adding coolant?
Absolutely not. On the contrary, your vehicle should be off and completely cool before you even think about opening the coolant reservoir and filling it up. Here’s why…
There are quite a few serious risks that could arise from adding coolant to a running vehicle, or even one that was just recently turned off and is still warm. The most notable is burn-related injuries.
A running engine generates immense heat, and the coolant system is pressurised. What happens when you open up that system while it’s hot? You could end up releasing scalding steam or fluid, causing severe burns.
That’s not all, though. There are also risks to your vehicle. Remember, coolant expands when heated. Introducing cold fluid to a hot engine can cause sudden temperature changes, potentially cracking the engine block or damaging other components due to thermal stress.
Safety aside, adding coolant to a running car is just not practical. A cool engine provides an accurate reading of the coolant level so you don’t have to stress about how much coolant to add.
So, where does the car need to be running when adding coolant misconception come from? Likely from the fact that you should run the car after adding coolant. This is known as bleeding the cooling system, and it’s an important step to remove trapped air pockets.
But for the sake of this conversation, just know that adding coolant to a running car - or one that has been turned off within the last 15-30 minutes - is not a good idea. You should always let your car cool completely before doing anything with the cooling system.
You might have other questions besides whether or not you should let your car run when adding coolant.
Where does engine coolant go in a car?
Which engine coolant for my car is best?
While you should bring your vehicle into a local shop if you don’t feel comfortable handling this task, it’s fairly simple. Here’s a quick guide to adding coolant to your car:
If you’re doing a complete coolant replacement you should learn how to dispose of antifreeze properly in our blog, as used coolant is a contaminant that poses environmental concerns. Otherwise, there’s only one thing left to do - get the best engine coolant at Jennychem today!
When it comes to maintaining your car’s cooling system, the quality of your antifreeze is just as important as how you use it. That’s why the UK’s vehicle owners and fleet managers trust Jennychem.
Our range of antifreeze solutions is formulated to meet the needs of all vehicles, providing superior protection for new and old cars alike, across all makes, models, and engine styles. Here are our most popular products:
Despite our premium formulations, you’ll enjoy affordable antifreeze prices, saving a lot of money compared to professional coolant flush and fill services. This is truly the best of both worlds.
You’ll also gain access to other vital fluids like Ad Blue for sale, car screen wash, windscreen de icer, and car cleaning products like car snow foam, traffic film remover, car shampoo, and so much more.
Give your vehicle the care it deserves. Shop today and see for yourself why Jennychem has been the UK’s trusted choice for more than 35 years in a row.
So, does the car need to be running when adding coolant? We’re glad you came here today, because it’s important to make sure your car is completely cool before attempting to add coolant. Failing to do so could put you at risk of serious injury.
Follow our tips on how to actually add coolant to your car and enjoy peace of mind protecting not just yourself but also your vehicle. The only thing left to do if you haven’t already is get your hands on the optimal antifreeze concentrate at Jennychem.
Stay safe in any weather with premium antifreeze formulations that adhere to British standards. Choose Jennychem and keep your cooling system performing at its peak, season after season!
