It’s that time again when your truck’s Cummins diesel engine needs an antifreeze change. And like any decent car owner you want to get the best for your truck. But when it comes to finding the best antifreeze for Cummins diesel, there are plenty of options.
But only a few can be considered the best. To help you on your search, we decided to tap into our experience with the 6.7 Cummins engine and compile a list of 7 antifreeze/coolants for 6.7 Cummins. We have also included a guide on selecting the proper coolant for a diesel engine.
We picked the Zerex Extended Life Red Heavy Duty (HD) Concentrate Antifreeze/Coolant... * (#ad) as our top choice. It offers a service life of 300,000 miles better than the other six on the list. Also, it protects against corrosion in newer engines.
Our second choice is the Mopar 10 Year/150,000 Mile Coolant 50/50 Premixed * (#ad). This offers a long service life as well, though not as much as that of the Zerex. The Mopar does come premixed, which makes your work easier, especially if you do not have experience diluting antifreeze.
A Quick Glimpse Of Our Top Rated Antifreeze For Cummins Picks
Please note that Prices and Availability Are Subject To Change
How To Know If Your Diesel Engine Coolant Needs Replacement?
First things first, how do you know it is time to change your 6.7 or 5.9 Cummins antifreeze? There are several signs to check for.
- Frequent overheating of the engine: If the temperature gauge on your vehicle is always high and your engine overheats more frequently than usual, it may be a sign that you need to change the coolant.
- A sweet smell from the engine: Coolants typically contain a compound known as ethylene glycol. This compound produces a sweet smell when it burns. The smell is similar to that of maple syrup or butterscotch. If you smell a sweet smell while driving, it may be a sign that you need to replace the engine’s antifreeze.
- Low coolant light on: When the coolant level in your vehicle is low, the low coolant level will light, indicating that you need to replace the coolant. It is essential to check the coolant levels weekly.
The Best Antifreeze For Cummins Diesel
Zerex Extended Life Red Heavy Duty (HD) Concentrate Antifreeze/Coolant
The Zerex extended life red heavy-duty antifreeze is the best coolant for 6.7 Cummins. It is Cummins 14603 approved and, according to the manufacturer, will be in service for 300,000 miles. So what makes this antifreeze such an excellent option for your diesel engine?
Firstly it contains denatonium benzoate as the bittering agent. This makes it a little bit safer for animals and kids who may be tempted to taste the highly toxic but sweet ethylene glycol. Speaking of ethylene glycol, this antifreeze uses virgin ethylene glycol.
As such, it should protect the lining of the cylinders from cavitation as well as protect the engine from corrosion and rust. This coolant does contain silicates, though and as such, will not be a good option if you want a silicate free coolant.
Mopar 10 Year/150,000 Mile Coolant 50/50 Premixed
The Mopar 10 year 150,000 miles is a pre-diluted coolant, one of the best 5.9 Cummins antifreeze. It comes premixed with water, meaning no mixing is required from you. And as you may expect from one of the best diesel coolants, it offers standard protection to your engine.
It contains ethyl glycol to protect against rust and corrosion. It will also protect the cylinder lining from liner pitting, scales, and voids. It protects against overheating and prevents boiling for up to 129 degrees celsius.
When it comes to its service life, it should last for up to 150,000 miles and will protect against freezing of up to -34 degrees celsius. Overall, this is an excellent coolant that does not require mixing with water or any other coolant.
PEAK PXAB53 Antifreeze Coolant, 1 gal, 50/50, Amber
The PEAK PXAB53 antifreeze coolant is a cheaper alternative to some of the other options on the market. But being cheap doesn’t mean it is of inferior quality. On the contrary, this silicate-free antifreeze offers great value for money.
As stated, the coolant is silicate-free, meaning it will not present problems of clogging the EGR or cooler. It also contains inhibitors to protect your engine from rust and corrosion. The inhibitors will also protect the lining of the cylinder walls from cavitation.
It will also work in most American, Asian and European car models. While it is a good value for money, it is not quite amber in color. It is more of a yellowish tint and is a universal coolant.
Motorcraft gold antifreeze/coolant
The Motorcraft gold antifreeze/coolant is designed explicitly for Ford engines. And like most modern coolants, it contains a bittering agent and protects against freezing, overheating, and corrosion.
We recommend adding this antifreeze with distilled water at a ratio of 50:50. And it should protect your engine from cold temperatures of up to -34 degrees c. It will also offer protection against overheating for up to 129 degrees celsius.
There are a lot of generic coolants out there, which costs less than this Motorcraft coolant. However, given this is designed for Ford engines, it will last longer and be better for your Cummins engine than any generic coolant.
FleetGuard CC2825 ES Compleat 50/50 Prediluted Extended Life Antifreeze/Coolant
Fleetguard is the brand of antifreeze recommended for the Cummins diesel engine. And there is no way we could not include it on our list of the best antifreeze for diesel engines.
It comes pre-diluted with distilled water at a 50:50 ratio giving you an easier task of adding it into the radiator. It has scale inhibitors to protect your engine and cylinder wall linings. But perhaps the best part is that it is free of phosphates and silicates.
Silicates and phosphates are known for clogging up the EGR and cooler over time and is why we feel silicate-free coolants are better for diesel engines. This coolant protects your engine from overheating and can withstand temperatures of up to 130 degrees celsius. It can also withstand temperatures of as low as -37 degrees celsius.
Zerex G05 Phosphate Free Concentrate Antifreeze/Coolant 1 GA
The Zerex 505 phosphate-free concentrate coolant is the best diesel coolant for the 5.9 Cummins diesel engine. It is approved by Cummins for use in its diesel engines and can also be used on European car models.
One of the reasons it is Cummins approved is that it is formulated using Hybrid Organic Acid Technology chemistry. This formulation protects against rust and corrosion. And while it does contain silicates, it is in a very low quantity.
The coolant is phosphate-free and uses virgin ethylene glycol. The coolant is gold in color and does not contain 2-ethyl hexanoic acid, which is found in Dex-cool coolants. This may be an issue for some people, but it means it won’t eat away at gaskets.
ACDelco 10-101 DEX-COOL Extended Life Coolant – 1 Gallon
Designed for new models, the ACDelco 10-101 dec-cool extended life coolant is a silicate and phosphate-free coolant that lasts for up to 150,000 miles. It can protect brass, cast iron, steel and copper components from corrosion.
The liquid is orange in color and minimizes the breakdown of metal parts that come into contact. It is compatible with engines that use Dex-cool coolants. However, you can use it on a vehicle not originally using dex-cool coolant.
You will have to replace the coolant after 30,000 miles, though. This concentration is formulated using Carboxylate technology, making it ideal for hybrid cars as well.
How to Change Antifreeze
Changing the antifreeze on a Cummins diesel engine is pretty straightforward. You will need a 5 or 6-gallon bucket and a funnel. Go under the driver’s side of the truck, and you should find a white dial at the bottom of the radiator.
Twist the dial to the left, and place the bucket under the radiator. The coolant should pour out into the bucket. This may take some time. To speed up the coolant drainage, loosen or remove the radiator cap.
Once the coolant has drained, tighten the white dial. Use a funnel to pour about half a gallon of distilled water into the radiator cap. Check for leakage under the radiator, and if there are no leaks, add the coolant.
Add about 2 or 2 ½ gallons of the coolant and top it off with water. You will notice that the radiator is overflown. Start the car’s engine to get the overflowing water and coolant to drop. You may have to drive to get the water to drop. Once this is done, close the radiator cap.
Things To Consider For Getting The Best Antifreeze for Cummins Engine
Not every antifreeze will work with your Cummins engine. Knowing what kind of coolant to buy for your engine is therefore essential. Here are some of the things you need to look for when shopping for the best antifreeze for Cummins diesel.
Pre-diluted vs. undiluted
Some antifreeze comes premixed with water. This is a good thing as it means you do not have to do the mixing. However, most antifreeze comes undiluted, and you have to dilute it with distilled water when adding it to the radiator.
Both antifreeze options are good, and it will depend on your preference. If mixing water and the antifreeze at the correct ratio gives you trouble, a pre-diluted choice will be ideal. However, if you want to control how much water you add to your antifreeze, go for undiluted.
Active ingredient
The active ingredient in almost all antifreeze is a compound known as ethylene glycol. This compound is highly toxic but very sweet. Because of this, modern coolants come with another ingredient known as a bittering agent.
The purpose of this is to make the ethylene glycol bitter to prevent animals and even kids from taking it. Whether a coolant has a bittering agent or not will not impact its performance. Other ingredients include silicates, phosphates, and nitrates.
Some coolants do not contain silicates or phosphates and can be better for diesel engines. The recommended coolant for the Cummins engine is actually silicate-free.
Antifreeze type
There are three main types of antifreeze used in diesel engines, inorganic acid technology (IAT), organic acid technology (OAT), and hybrid organic acid technology (HOAT).
Inorganic acid technology:
These types of antifreeze are common in older cars, particularly those made before the mid-1990s. These coolants use silicates and phosphates to protect metal parts from corrosion and are usually bright green in color. These coolants should be flushed out after every 30,000 miles
Organic acid technology:
These types of coolants are used in newer car models and do not contain silicates or phosphates. Instead, they contain carboxylic acids to inhibit corrosion. The colors of these coolants range from pink, orange, bright red, blue, and dark green. It is recommended to flush out these coolants from the cooling system after 135,000 miles.
Hybrid organic acid technology:
These are the newest types of coolants and are a blend of IAT and OAT. They are found in most modern cars and are usually yellow, pink, turquoise, blue, or purple in color. These coolants need to be flushed after every 150,000 miles and contain added silicates and phosphates.
So what is the best coolant for diesel engine? Hybrid organic acid technology-based coolants are recommended for diesel engines and, in particular, for Cummins diesel engines.
Temperature Range
The primary purpose of the coolant is to protect the engine from overheating and freezing. As such, the temperature range it can withstand will also be necessary. The best antifreeze for diesel engines will typically be able to withstand temperatures as low as -34 degrees celsius.
They will also be able to withstand temperatures of as much as 129 degrees Celcius.
Frequently Asked Questions
What kind of coolant does a Cummins diesel use?
According to the manual, the Cummins diesel uses an antifreeze with hybrid organic acid technology or HOAT. The manufacturer recommends using coolants with this technology.
Is there a special antifreeze for diesel engines?
Yes, the antifreeze used on diesel engines typically contains supplemental coolant additives or SCA. These additives help to protect the cylinder walls from corrosion and erosion.
How many gallons of antifreeze does a 6.7 Cummins take?
The 6.7 Cummins engine holds 5 gallons of antifreeze and distilled water mixture mixed in a 50:50 ratio. This means 2.5 gallons of distilled water and 2.5 gallons of coolant.
What is the Capacity of the 12 Valve Cummins Engines for Antifreeze?
The 12 valve Cummins engine holds a capacity of 6 gallons of distilled water and coolant mixture. This means 3 gallons of coolant and 3 gallons of distilled water.
Are Coolant and Antifreeze the Same Thing?
Not precisely; antifreeze refers to the liquid used in a car’s cooling system. It is usually a thick liquid. On the other hand, Coolant is the mixture of antifreeze and distilled water mixed in a ratio of 50:50.
Conclusion
The Cummins engine requires specific coolants, and not every antifreeze will work. The 7 above will be safe to use with this engine, and some of them are recommended by Ford for the Cummins engine. Overall, you should be able to find the best antifreeze for Cummins diesel for your truck from among the seven above.
Last Updated on January 29, 2024 by Rifen
