How Long Can You Run A Car Without Coolant?

Most people know that coolant is one of the most critical fluids in your car. Unfortunately, coolant leaks are relatively common, and coolant itself can be somewhat expensive. Coolant is even more costly if you’re driving a luxury car or a foreign car brand that doesn’t use a standard coolant mixture. 

Those problems can all make it fairly common for people to ask if it’s possible or safe to run their vehicle with little or no coolant. So, how long can you run a car without coolant?

It depends a little on what you mean. If you’re talking about how long you can safely run a car without coolant, that’s a very different answer than if you’re talking about how long a vehicle will physically run without coolant in its system. We’re going to assume that most people don’t want to risk serious damage to your engine and other internal systems, so we’ll stick to the first answer. 

Ideally, you should never run your vehicle without coolant. Running too hot can damage many internal components, and heat builds up in your vehicle’s engine incredibly quickly. After all, the engine is home to small rapid-fire explosions that power the pistons, and all those explosions let off heat. 

However, if you absolutely must start your car without coolant, it can probably run for about a minute without too much risk of damage. You may be able to get away with as much as 5 minutes of running without coolant, depending on the engine, car model, and how hard you’re asking the engine to work. 

It's not a good idea, though. Even with those incredibly short runtimes, there's still a risk of severe and even potentially dangerous internal damage to your vehicle. 

Why Does Your Car Need Coolant?

The primary purpose of coolant is to transfer heat away from the engine. It absorbs a lot of heat very quickly and then also releases that heat fairly quickly. That way, the coolant can maintain a roughly even temperature across your engine and prevent excessive overheating. Coolant also helps to equalize the internal temperature under the hood of your car entirely. 

Coolant must have a very high boiling point and a very low freezing point since it can only do its job properly when it’s in liquid or mostly liquid form. 

Beyond just having coolant in your vehicle, it’s also essential to make sure you have the right kind of coolant for your vehicle since it needs to be the correct choice for the temperature range your engine can handle. 

Your coolant also needs to be mixed appropriately for the right temperature balance. Some brands need 100% coolant, while others need coolant mixed with some distilled water. 

How Often Do You Need to Change Your Coolant?

The rate you need to change your coolant depends a lot on the kind of coolant you're using and the kind of car you have. Older vehicle models were once recommended to have their coolant changed every two years or so. That's less important now since coolant formulas have improved, and they last longer without changing their chemical properties. 

Newer car models may come with a recommendation to change the coolant every 5-10 years, but the exact range varies depending on the car model and the type of coolant. For cars and coolants in this range, it's generally a good idea to change your coolant every 200,000 miles or so. 

More recent models and some luxury vehicles may even have come with the only coolant they’re likely to need, barring damage to the coolant system, of course. 

Which Coolant Should I Buy? 

If you’re getting your coolant changed or refilled by a professional mechanic, you probably don’t have to worry too much about this detail. The shop will be able to look up which kind of coolant to use, and they’ll only use that coolant. You can also ask them what type of coolant to buy if you want to keep some emergency coolant around. 

Some shops will even order an extra container for you since they might get a discount on the price. They’ll just give you the coolant when you come to pick up your vehicle. 

However, if you’re choosing coolant for yourself, things can get more complicated, especially if it’s an emergency and you don’t have any available in your car.

While some 'universal' coolants will work in a pinch, almost all of them will offer lower performance than the right coolant for your car. You can use them if you need coolant and don’t have another option, but long-term use of universal coolants can lead to engine damage and other problems over time. 

Your owner’s manual should tell you which coolant your car needs. Most auto parts stores will have a selection of coolants to choose from. If they don’t have the right coolant for your vehicle, you can ask them to order it. Most auto parts places won’t mind placing a small order for a customer, especially for essential supplies. 

What Happens When You Run A Car Without Coolant?

If you try to run a car without coolant, it’s relatively predictable what will happen next. Since coolant is the primary system responsible for reducing your engine’s heat, that's the first place you'll see the effects of running without coolant. 

Airflow and other possible cooling factors can’t keep up with the heat produced in your engine. So the heat in your engine will rise rapidly. Usually, within a few minutes, you'll have enough heat to risk the moving parts of your engine deforming. Seals and gaskets in and around the engine may also be damaged and might need replacement if you run your car without coolant. 

In more modern vehicles, you’ll probably have a bunch of warning lights come on right away. Your coolant sensor warning light at least should come on, and you’ll probably start getting temperature warnings, and your check engine light may also come on shortly after that. 

If you insist on running your car, you’ll likely have more permanent engine damage and are risking even some potentially dangerous kinds of damage under the hood. It’s not uncommon to start seeing smoke coming out from under the hood if you keep running. 

Modern vehicles mostly have an automatic shutoff system that will cut off the engine before it can cause too much damage to the rest of your car. However, the automatic shutoff usually can’t be trusted to prevent damage to your engine. Older cars don’t have those safety measures, so they are usually more dangerous to run without coolant.