If the vehicle suddenly loses its warm air, the mechanic will open the hood and point to the mottled and corroded EGR cooler to tell you, “Because the wrong coolant was chosen, the repair cost will be at least $2,500.” Such a scene is by no means an exaggeration. In the maintenance of 6.7 Cummins engines, the selection of coolant is a “matter of life and death” that concerns both performance and one’s wallet. ​

6.7 Cummins Engine Coolant

Why Is The Selection Of Coolant Crucial? ​

Some people, lured by low prices, used coolant that was not recommended by the original manufacturer. As a result, within just three months, the EGR cooler was corroded and riddled with holes. Not only was the high maintenance cost high, but the transportation period was also delayed, resulting in heavy losses. There are still many car owners who, due to the mixed use of coolants with different formulas, have experienced sedimentation blocking the heating system. In the cold winter, they can only shiver in the icy cab. These painful lessons are all warning us: Choosing the wrong coolant can lead to endless troubles!

The core function of coolant

Coolant is not merely about preventing the engine from “overheating”. In severe cold, it can act like a loyal guard, preventing the cylinder block and turbine from cracking due to freezing. In the scorching heat, it can also prevent the coolant from boiling and protect the normal operation of the engine. More importantly, it also shoulders the important responsibility of anti-corrosion, safeguarding the key aluminum components of the engine and extending their service life. In addition, for vehicles equipped with DPF systems, the appropriate coolant can prevent ash residue and avoid malfunctions in the after-treatment system. It can be said that choosing the right coolant is like buying a “lifetime insurance” for the engine. ​

Technical Parameters: Four Major Indicators That Must Be Paid Attention To

• Formula type

In the world of coolant formulas, there are quite a few tricks to it. The NOAT (Organic acid-Free technology) coolant officially certified by Cummins, such as Fleetguard ES Compleat, is like a “safety guard” and can be perfectly adapted to the engine. However, HOAT (Mixed Organic Acid Technology) coolant is fraught with risks. Some of its products contain phosphates that can cause damage to aluminum water pumps. There are still two types of “forbidden foods” that must be avoided: silicate formulas are prone to causing precipitation, and nitrite formulas can lead to DPF poisoning. Remember, choosing the wrong formula is like planting a “time bomb” in the engine.

• Freezing point and boiling point

The freezing point and boiling point of the coolant are directly related to the engine’s survival ability in extreme environments. A 50% ethylene glycol concentration is a magical equilibrium point that can achieve a freezing point of -37 ℃ and a boiling point of 129℃. However, if you often drive at high altitudes, the boiling point will drop by 1℃ for every 300 meters of elevation increase. At this point, you need to adjust the coolant concentration according to the actual situation; otherwise, the engine will “boil over” for you in no time.

• Additive Package (DCA)

DCA4 corrosion inhibitor is the “golden partner” of coolant and its concentration must be maintained at 1.2-1.8 units per gallon. Here’s a little trick: By using test strips, you can easily grasp the concentration of DCA4. However, it should be particularly noted that coolant containing boron formula must never be used. It will have a chemical reaction with the cylinder liner coating, seriously damaging the engine.

• Compatibility certification

Recognize the CES 14603 standard, which is a mandatory requirement of the Cummins engineering specification. Those coolants labeled as “universal” may seem convenient, but in fact, they may cause electrolytic corrosion of sensors. Just as wearing ill-fitting shoes can scratch your feet, using incompatible coolant will gradually “torment” the engine. ​

Which Products Are Trustworthy? ​

Original factory recommendation

Fleetguard ES Compleat is the only OEM coolant certified by CES 14603. It can be called “original factory exclusive” and its quality is absolutely guaranteed. If you want to choose an alternative solution, Valvoline Zerex G05 is also a good choice, but DCA4 needs to be added additionally.

Third-party brand Red and Black List

Among third-party brands, Shell Rotella ELC stood out with its nitrogen-free ammonium formula, and Peak Final Charge premixed deionized water was also highly praised. But be careful to avoid those cheap “heavy-duty general-purpose” coolants, whose sulfate ash content is > 1.5%, and the green coolant containing phosphate. Using them is equivalent to “slow suicide”. ​

Authentication Query Tutorial

Do you want to know if the coolant you chose is reliable? Through the Cummins QuickServe online system, by inputting product information, compliance can be verified with one click. This “truth verification magic tool” must be put to use! ​

Selection Strategies Under Different Demands

• Daily commuting

For daily commuting vehicles, premixed 50% concentration NOAT coolant is a cost-effective choice, providing sufficient protection without increasing costs. But remember, never use high-concentration ethylene glycol coolant. It will increase the load on the water pump and is not worth it.

• Heavy load/towing

If your vehicle is frequently overloaded or towed, it’s time to upgrade the coolant configuration. A 60% concentration coolant combined with an auxiliary radiator, such as Mishimoto MMH6X-RD, can effectively cope with high-load operation. Detecting concentration attenuation with a refractometer every month is a “compulsory course” to ensure engine safety.

• Extremely cold/extremely hot environment

In extremely cold regions with temperatures as low as -40 ℃, propylene alcohol-based coolant can sacrifice its boiling point in exchange for a lower freezing point, enabling the engine to operate normally even in icy and snowy conditions. In the high-temperature environment of the desert, adding a 1.5bar high-pressure cap to raise the boiling point to 127℃ can prevent the engine from “heatstroke”.

• Modify the engine

For engines modified with large turbochargers, low-viscosity coolants, such as Evans Waterless, can reduce flow resistance and improve performance. However, if it is a track competition, adding Water Wetter temporarily should be done with caution. It must be thoroughly rinsed after the race; otherwise, hidden dangers will be left.

Common Misunderstandings And Fatal Mistakes About Coolant

• Color misguidance

Many people think that coolants of the same color can be mixed and used, which is a big mistake! Once the green HOAT and the green NOAT meet, they will form a gel-like substance, blocking the engine pipelines. Color is just the appearance; the formula is the key.

• Blending with tap water

Some people mix coolant with tap water to save money, which is simply “drinking poison to quench thirst”. Data shows that chlorine-containing tap water can increase the corrosion rate of aluminium by 300%. Saving a small amount of money but having to spend a lot to repair the engine, no matter how you calculate it, it’s never worth it.

• Long-lasting coolant maintenance-free? ​

Don’t be misled by the word “long-lasting”. The DCA4 additive will become ineffective after five years and the test kit must be replenished. Thinking that long-lasting coolant doesn’t need to be taken care of is as absurd as believing that a car can run for a lifetime with just one refueling.

• Reuse of second-hand coolant

Reusing second-hand coolant may seem environmentally friendly, but in fact, it hides risks. Excessive TDS (Total Dissolved Solids) can lead to cavitation in the cylinder liner, causing the engine to be full of holes. This kind of practice of losing the big picture for small gains must never be tolerated.

Conclusion

Choosing 6.7 Cummins engine coolant is like picking a “personal bodyguard” for the engine. From formula types to application scenarios, from brand certification to common misunderstandings, no link can be taken lightly. Remember these key points and avoid those “pitfalls”, and your engine will be “healthy and long-lived”, accompanying you to travel thousands of miles. Next time when you change the coolant, don’t make a choice in a daze!

QSB 6.7 Cummins Engine