Like many other fluids and lubricants, engine coolant unfortunately falls into the “change it and forget about it” category for many vehicle owners. However, neglecting your cooling system maintenance, including replacing your coolant on a regular interval, can possibly result in serious engine damage due to overheating. Furthermore, the quality of engine coolant is a vitally important aspect of engine temperature control. As such, if you are looking to flush and replace your coolant to keep your engine in good health, this guide will help you determine the best coolant brands to keep your engine cool as well as provide information about engine coolant.
Function Of Engine Coolant
As the name suggests, the function of engine coolant is to absorb engine heat as the coolant passes through the motor, and then to shed the absorbed heat to atmosphere when the coolant passes through the radiator. Thus, by continually absorbing and shedding heat, the engine coolant is the principal agent that controls and regulates the temperature of the engine. The coolant is circulated through the engine via the water pump.
Coolant itself often has two main components: anti-freeze and water. Most commonly, these are mixed in equal parts depending on the vehicle application and climate. Often, you can find coolant that is pre-mixed (often referred to as 50/50). There is a great deal of debate regarding which type of water should be used when mixing your own coolant. We should note that we generally do not recommend using tap water due to the additives and mineral content that can have negative effects on your cooling system. We recommend following the directions in your owner’s manual as well as the instructions on the container for the coolant that you choose. As far as the anti-freeze component, it is designed to raise the boiling point and lower the freezing point (hence the name) of your coolant, making it suitable for use in a wider variety of climates. Additionally, anti-freeze often contains anti-corrosive agents designed to protect your engine.
It should be noted though that although all engine coolants have the same general purpose of regulating the engine temperature, there is no single coolant that offers the same level of protection against corrosion and over heating/freezing in all engines under all possible operating conditions. The main reason for this is that unlike older engines that were made mostly of cast iron, modern engines are made with a wider variety of various metal alloys including aluminum, steel, and magnesium. Some engine and cooling system components could also contain varying amounts of silicone, copper, nylon, and other plastic or rubber compounds.
The result for the above is that the engine coolant required by any given vehicle could differ by make, model, production year, country or region, and where a specific vehicle was produced. Therefore, it is imperative to know what type and formulation of engine coolant the manufacturer of your specific vehicle recommends in order to obtain the highest possible level of protection against corrosion, electrolysis, and the effects of extreme temperatures on the metals/materials in your vehicle’s engine.
It is also important to be aware that mixing different coolant formulations or types could cause the active ingredients in the two formulations to reduce the effectiveness of each other. As such, we strongly suggest you follow the recommendation of the manufacturer of your vehicle when choosing coolant, as getting it wrong can be a costly mistake.
NOTES ON ENGINE COOLANT COLORS
Although most manufacturers of engine coolants use colors such as green, orange, red, blue, and pink to prevent cross contamination of different coolant formulations, there are never any guarantees that all coolant manufacturers in all parts of the world always follow the same conventions. Therefore, the color of the coolant in a given vehicle must never be taken as evidence that the correct (or otherwise) coolant had been used to fill the cooling system.
The ONLY way to be sure that you are choosing the correct coolant for your vehicle is to obtain the relevant information from the vehicle manufacturer. This information can often be found in your owner’s manual or on a sticker in your engine bay (typically located on or near the radiator fill cap).
Common Symptoms Of Bad Engine Coolant
The symptoms and signs of degraded or unsuitable coolant are much the same across all applications, and could include the following:
Increased Engine Temperature
This is usually caused by the formation of scale on the internal surfaces of the engine and/or cooling system as a result of the reduced efficiency of corrosion inhibitors in the coolant. It can also be associated with incorrect mixture ratio or using water that is too mineral rich. In practice, the scale prevents or inhibits the transfer of heat from the engine to the coolant. Scale can also build up to the point that is limits coolant flow to certain portions of your engine, which can cause a variety of severe problems due to localized heating ranging from detonation (pinging) to engine failure.
Coolant leaks could appear anywhere in the cooling system as the result of corrosion affecting sealing surfaces for fittings, hoses, and seals. Typical leak sites include water pump seals, thermostat housings, heater cores, and cylinder head gaskets. Often, the first sign of coolant leaks is decreasing coolant levels over time, as the actual coolant leak may not always be immediately apparent or visible, especially if it is small.
Replacing Engine Coolant
It should be noted that while topping off the engine coolant level is usually a simple and straightforward procedure, the process of draining, flushing, refilling, and purging a modern cooling system can be a little more difficult, although still doable for most DIY mechanics.
Be aware that failure to replace your coolant according to proper procedures per the vehicle manufacturer could cause air to remain trapped in the cooling system, which will almost certainly cause circulation issues, with engine overheating and possibly engine failure as a consequence.
Note: The example steps below are intended for general informational purposes solely to help give you an idea of project difficulty and tools required. As all cars are engineered differently, repair procedures and safety hazards vary from vehicle to vehicle. To ensure that you have a vehicle specific repair procedure and an exhaustive list of potential safety hazards, we advise you reference a factory service manual for your vehicle. Similarly, referencing a repair manual such as Chilton or Haynes might serve as a less expensive alternative.
Step 1 – Identify the correct type and mixture of coolant for your vehicle as well as the coolant capacity so you know how much to buy. This information could be located in your owner’s manual, on a sticker on your radiator or radiator cap, in a factory service manual, and/or in a repair manual specific to your vehicle.
Step 2 – Allow the engine to cool down completely to prevent risk of burns (coolant is very hot when the engine is at operating temp!), and open the fill cap once cool.
From here, you may need to jack your car up using an appropriately rated floor jack and support it with jack stands in order to access the bottom of the radiator. Find and locate the radiator drain plug and open it to allow the coolant to drain out of the engine. This can usually be accomplished with a ratchet and socket. If there is no drain plug on your radiator, you can also drain the coolant by disconnecting the lower radiator hose. Either way, be sure to collect the coolant in a suitable drain pan for safe disposal later on. You can use a screwdriver to remove the clamp holding the lower radiator hose in place if you need to drain the coolant in this fashion.
Be sure to reconnect the radiator hose or reinstall the drain plug as soon as the coolant has all been drained. You may wish to replace the hose clamp for the lower radiator hose if you remove it, depending on its condition. Lastly, as you are working under your car, it is always worthwhile to don a pair of safety glasses to protect your eyes from splashing coolant.
Step 3 – Once the coolant is drained, some vehicles call for the circulation of fresh fluid throughout the cooling system in order to purge any remaining old fluid or contaminants. Usually, this requires getting the vehicle up to operating temp to open the thermostat and turning the heater on to flush the fluid out of the heater core. Once you have circulated coolant, you can turn the vehicle off, wait for it to cool down to prevent possible burns, and then drain the fluid again per Step 2 above. We don’t recommend a secondary flush by default unless your vehicle requires it, and encourage you to check your repair manual to see if and when this step is required.
Step 4 – Make sure the radiator drain plug and/or lower radiator hose have been reinstalled properly to avoid spilling coolant. Mix up the required volume of coolant to the correct concentration, and refill the cooling system through the fill cap on the radiator or expansion tank until it reaches the appropriate level (and also open bleed screws as required). Note though that there may be air trapped in the system so even though the level reads correctly, you may still need to add more coolant after idling the vehicle for a couple minutes. During this time, keep an extremely close eye on your temperature, as your car can quickly overheat if air remains trapped in the system. Note that after idling your vehicle, your engine and coolant will be hot and pressurized. Opening the cap before it cools can result in boiling coolant that can burn you if it splashes on you.
Step 5 – Once the cooling system is full and you are confident that there is no air in the system, double check all bleeding screws to confirm that they are closed, carefully lower the car back to the ground, and perform a careful test drive to verify that the cooling system is working correctly and that the temperature gauge reads normally.
We recommend keeping an eye on your coolant level for the first few drives to make sure there isn’t any residual air in the system that would bleed off and require you to top off your coolant. This can also help you verify that everything was reassembled correctly and that there are no leaks, which would be a potential cause if your coolant level keeps dropping.
Best Engine Coolant Brands
There are many engine coolant brands to choose from out there. Before selecting a coolant, we strongly urge you to double check the appropriate coolant type for your vehicle. Mixing incompatible coolants or adding a coolant not suitable for your vehicle could result in costly repairs. That said, below are some choices that will help you choose the best coolant brand for your application.
Engine Ice coolants are made to meet or exceed the relevant ASTM and SAE standards, which is the minimum requirement to be approved for use by vehicle manufacturers. Engine Ice coolants are also free of silicates and phosphates and contain de-ionized water, making them generally non-toxic and potentially slightly safer for the environment. Engine Ice coolants provide effective engine protection across a broad temperature range. Engine Ice makes high quality coolant and as such, we can confidently recommend them.
Peak coolants are available in two forms; pre-diluted for topping up coolant levels, or concentrated to allow users to mix their own quantities. Note that Peak pre-diluted and concentrated coolants are available in a wide variety of formulations to suit the specific needs of almost all vehicle makes and models in the North American market. Peak coolants also come with a limited warranty, which should make it an easy choice for use in all applications where it is appropriate.
Note that unlike the other coolants listed here, Evans coolants typically do not contain any water, since the coolant itself is based on high-purity propylene glycol and various application-specific additives. Moreover, since the coolant does not contain water, Evans products provides effective protection against freezing and overheating from temperatures for an extremely wide range of temperature. Overall, Evans makes a solid product that we believe should serve you well.
Prestone coolant formulations can provide effective protection against corrosion, freezing, and overheating for a very long time depending on conditions and application. More to the point though, most Prestone coolant formulations are compatible with most other coolant formulations made by competing manufacturers, which makes a Prestone coolants flexible for when you have to top off your coolant levels between scheduled services (as always, verify compatibility before adding any coolant to your vehicle). We suspect that you will be happy if you decide to use Prestone coolant for your next coolant change.