What is engine coolant?

Diagram of a conventional gasoline engine cooling system, with heater core.

Gasoline and diesel engines aren’t that efficient. Even in today’s most efficient engines, only about 40% of the energy released from burning fuel actual moves the vehicle; most of the rest is lost as heat. Your vehicle contains a cooling system to get rid of that extra heat and keep your engine at the right temperature. Most cooling systems are filled with a liquid coolant (also called antifreeze) that absorbs heat from the engine and then carries it to a part called your radiator, where it is given off to the air. To prevent this liquid from freezing during the winter and damaging your engine as it expands, coolants contain a chemical such as ethylene glycol – hence the name antifreeze.

Some of the waste heat is also used to heat the interior of the vehicle as needed, using a miniature radiator called a heater core.

Hybrid and electric vehicles, while having no engine, still contain cooling systems in order to regulate the temperature of the battery pack; electric motor; and other electric drive system parts. Many of these systems use a liquid coolant as well.

Why does coolant need to be changed?

rust in radiator
An extreme example of rust build-up in a very neglected cooling system. Once this process starts, the rust is almost impossible to get rid of!

Like all other automotive fluids, coolant can’t do its job effectively forever. Most importantly, its freezing point increases over time. While new, properly mixed coolant will not freeze until temperatures reach around -40 °C, this freeze point gradually increases to the point where your engine could become damaged during a cold snap.

The pH of coolant also changes over time, with many coolants becoming acidic as they age. Because many of the cooling system parts are metal, this starts a process called electrolysis which causes rapid corrosion and damage to those parts. (The acidic coolant starts to act like the acid in a battery, and the coolant begins to hold an electrical charge.)

Coolant also contains several additives that eventually wear out, like corrosion inhibitors and water pump lubricating agents. Once these corrosion inhibitors stop working, rust and oxidation start building up inside the system; causing all kinds of issues. The best way to protect your cooling system from leaks and failure of its many parts is to flush and replace the coolant regularly.

How often does coolant need to be changed?

airdrie auto repair
Whenever we inspect your vehicle, we use test strips to measure the freeze point; pH and reserve alkalinity of your coolant.

Older vehicle with conventional green coolant required a coolant replacement every two years.

Most of today’s vehicle use a “long life” coolant that only requires replacement around every 5 years, or 160,000 kilometers; whatever comes first. Service intervals vary from vehicle to vehicle, so be sure to check your owner’s manual for your manufacturer’s exact recommendation. We can also look up these service intervals for you.

We can also test some of the qualities of your coolant, using test strips or various special tools.

Would you like some HOATs in your OATs? Making sense of different coolant types:

Years ago, almost every vehicle sold in North America used the same coolant; usually dyed a green colour. More recently, though, things have become a lot more complicated. Coolants today are classified by the type of corrosion inhibitors used in them:

  • Inorganic Acid Technology (IAT) coolant is the traditional green antifreeze used in older vehicles, with a 2 year service life.
  • Organic Acid Technology (OAT) coolant, with a 5+ year service life.
  • Hyrid Organic Acid Technology (HOAT) coolant, with a 5+ year service life.

Most of the time, these coolant types should NOT be mixed. Mixing the wrong coolants together can result in accelerated corrosion inside your cooling system; formation of solids or “gunk” floating in the coolant; or even rare situations where the coolant solidifies to a toothpaste-like consistency. Modern coolants are designed to protect a specific cooling system, where the radiator; engine block; and other parts are made of specific materials.

  • Asian vehicles traditionally have used coolant that does not contain silicates, but does contain phosphates.
  • European vehicles are usually the opposite; using coolant that does not contain phosphates but does contain silicates.
  • Many North American vehicles require a coolant with no silicates or phosphates.

Why coolant colour doesn’t matter anymore:

airdrie coolant flush
Here are four coolants that have about the same colour, but they are not compatible with each other!

Today, antifreeze is solid in almost every colour under the sun. However, you should NOT rely on colour to determine if a coolant is correct for your vehicle.

Many coolants that are the same colour should not be mixed, and some coolants with different colours can be! But fear not: at My Garage, we’re real automotive nerds and you can count on us to supply and install the coolant that is right for your vehicle. We stock over 15 different OEM coolants in order to service your vehicle properly.

Distilled water, and doing the little things right:

airdrie antifreeze leakingMost of the genuine, OEM coolants that we carry are concentrated, and need to be mixed with water before going in to your vehicle. The ratio of antifreeze to water will affect the freezing point of the coolant. A 50/50 mixture usually results in freeze point of around -37°C, while a stronger mixture will perform even better. However, a mixture stronger than 60% antifreeze/40% water mixture isn’t advisable, since the coolant will lose its ability to absorb engine heat.

When mixing coolant for your vehicle, we always use bottled, distilled water. This is one of those “little things” that won’t make a noticeable difference in the short term, but will make your vehicle more reliable in the long run. Distilled water contains far less of the minerals and impurities that cause corrosion in your cooling system, and also helps coolant additives last longer.

Coolant leaks:

airdrie radiator
Some coolant leaks will never drip on the ground, because the coolant evaporates off the hot parts! Some coolants will leave some noticeable staining behind when this happens.

If your vehicle is leaking antifreeze, this should be repaired as soon as possible. If your coolant level becomes too low, this could result in an overheating engine, and possible engine damage. In hybrid and electric vehicles, the risk of damage to expensive components from a cooling system failure is even greater.

Identifying the source of a coolant leak usually only involves a quick, inexpensive visual inspection. In cases where a leak is harder to locate, or only leaks under certain conditions, we may have to perform a cooling system pressure test to determine what’s wrong.

Do you have a cooling system issue? Count on My Garage to repair it properly, the first time – and for a fair price. We’ll also back the repair with the best parts and labour warranty in Airdrie.

Replacing coolant/antifreeze in Airdrie:

The process of replacing your coolant is often referred to as a coolant flush. When done properly, this procedure involves several steps:

  1. Drain the old coolant and engine block of the old coolant.
  2. Use a coolant flush machine or other means to flush out the system, in order to remove any remaining old coolant; build-up or debris. Special attention is paid to areas like the heater core, where dirt and gunk are most likely to settle.
  3. Fill the system with the correct mixture of genuine OEM coolant and distilled water.
  4. Bleed air from the cooling system. We use a special vacuum filling tool when filling the system, which mostly takes care of this. Any air that is not properly removed can result in an air lock, which can cause overheating or other damage.
  5. Visually inspect for obvious leaks and test drive the vehicle to confirm that the thermostat; cooling fan; and other system parts work properly.

For the best quality coolant flush in Airdrie, or if you have any coolant-related questions, please don’t hesitate to get in touch with us!