8 Best Oil For 6.7L Cummins (Review & Buying Guide) in 2023

Lubricating engines with a good oil brand can give a smooth and long run to a vehicle. If you have a Cummins 6.7, finding a good oil match is hard work.

Unfortunately, engine oil usually makes or breaks the performance. So, you need to pick a choice carefully.

So, you must own a top-notch &high-performance product that is worthy of your acquisition. Now it must be difficult for you to decide which oil can suit your preference.

I will recommend superior, premium & fantastic oils for 6.7 Cummins, which can be a fine handy for your vehicle that will extend engine life.

So, which is the best oil for Cummins 6.7?

Recommended oil for Cummins diesel Engines

#1. Valvoline SAE 15W-40 Diesel Engine Oil

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Valvoline Premium Blue is great engine oil that provides ultimate protection and enhanced performance. And if you want to decrease your engine wear exclusively, then Valvoline’s product has just got you covered. This oil comes with epic equipment. Its emission treatments include- Diesel Particulate Filters (PDF), Exhaust Gas Recirculation (EGR), etc.

One thing that will not bother you at all is the oil draining from engine parts. Such types of incidents generally annoy the engine drivers most. If you don’t want those problems, you must give a second thought to Valvoline’s diesel engine oil.

Main Features and Benefits to Use:

One solution technology

The one solution technology of Valvoline Premium Blue is highly suitable for a wide range of applications. Such as natural gas and gas applications, diesel including heavy-duty engines, and so on.

Oxidation resistant

Here, the oxidation-resistant capabilities are going to charm you. That is because they hold elevating temperatures and ensure a long oil life. So, if you have a heavy-duty engine, then you must give this product a shot.


The unique design of Valvoline Premium Blue conveys the professionalism of American-made heavy-duty diesel trucks. This design means the maintenance is going to be very easy and go well in rough terrain. Also, this oil will not affect the interior design at all and up to the mark even at tight spots.

API, SN, SM Standards

Valvoline meets all the significant standards, like API, SN, and SM. It is a sign that this oil will give excellent protection against Timing Chain and Low-Speed Pre-Ignition (LSPI). So, it is good news for your engine that it will last for a long time.


An issue that most of the engine oils bother us with is not gaining compatibility with all vehicles. That obstacle will be far away from you once you own this oil. It is one of the best handy you can ever have for your tractor, lawn equipment, trucks, cars, and so on.

Heat protection

Does your engine heat up frequently? Then a better substitute for that solution will be a high-quality oil, like Valvoline. It not only cools down the engine parts but also ensures a worthy performance of engines.


  • Ingredients: Synthetic
  • Viscosity: 15w40
  • API SN, SM: Meets
  • API gasoline categories: Meets
  • Vehicle service type: Truck
  • Liquid volume: 3 gallons


  • Has the ability to give utmost wear resistance to engine parts and prevents the engine from all barriers. Moreover, it extends the life of engines and helps them to stand in high performance.
  • This oil increases fuel efficiency with its low viscosity consumption.
  • Helps to reduce the maintenance of vehicles and makes them run thrillingly at rough terrains.
  • Cools down the engine parts when they reach the limitations of heat and certainly hold engines’ good performance.


  • The bottle seems to be leaky, which often wastes some amount of oil.
  • Though it works well locally, not a good one for commercial use.

#2. Shell Rotella T6 5W-40 Diesel Engine Oil

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Shell Rotella owns one of the best diesel engine oils. Here, you will get uncountable benefits because of its whole synthetic ingredients, such as more minor frictions, fewer impurities, better function in extreme weather, advanced protection, and a precise engine. And the best part about this oil is, it can ensure a prolonged engine life of any car.

Moreover, the fuel economy performance of this product compels it to merge in a high position anywhere. And, we know how harmful are the exhaust emissions that come out from cars and vehicles.

Thinking about durability? Then this oil will be your best friend on that part. Because, till now, we got no offense regarding its duration of serving.

Main features and benefits to using:

Improved deposit control

You will not have to spend any amounts on fuel consumption anymore. There are advanced dispersant additives in this oil which has multifunctional properties.

And because of that, your engine will have good protection against dirt, soot, and other contaminants. Significantly, the heavy-duty engines will get a natural aid once they get OK lubrication of Shell Rotella’s engine oil.

Improved heat resistance

Shell Rotella T6 leaves no stone unturned to resist the breakdown of any particular engine. All it does is maintain continuous protection in times of the service intervals. And, it will be great if you use this oil as the main priority for your heavy-duty engines.

Emissions system compatibility

With the advanced low-ash formulation, this oil helps to control blockings and poisonous exhausts of engine parts. Furthermore, you will have excellent compliance with vehicle emissions and diesel fuel efficiency.

Outstanding shear stability

Shell Rotella T6 heavy-duty engine oil does not let any viscosity loss happen and maintains optimal pressure. Hence, your heavy-duty diesel engine is going to be occupied in all terms.

Additive technology

When the engine parts don’t get proper lubrication, they often rub themselves vigorously. As a result, it affects the gas mileage. On that note, you must make sure that you lubricate your engine with the perfect oil.

And when the oil comes with additive technology that avails like a cherry on top because of ensuring longevity.


  • Ingredients: Full Synthetic
  • Viscosity: 5w40
  • API SP/SN PLUS/SN: Does not meet
  • Liquid Volume: 128 Fluid Ounces
  • ILSAC GF-6: Meets


  • Has improved fuel economy and wear performance
  • Saves a considerable amount against fuel consumption
  • Does not let the consumers compromise on durability and engine protection
  • Keeps the engine away from dirt, soot, and other contaminants
  • Resists breakdowns and controls blockings of engine parts


  • The rebate does not apply to all types of engines

#3. Valvoline Premium Blue 5W-40 Full Synthetic Diesel Engine Oil

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Valvoline Premium Blue 5w40 is superior engine oil that can provide extreme performance to any diesel engine. In addition, this oil will protect your vehicle in times of emissions and modern treatment that equips the diesel engines.

So, if you have engines with Diesel Particulate Filters (PDF) and Exhaust Gas Recirculation (EGR), you must try this oil.

What makes this product exceptional is its premium lubricant. However, your vehicle will not have to wait anymore for good temperature resistance. Valvoline 5w40 offers longer oil change intervals; it will make it easy for the vehicles to perform better throughout the route.

And that performance will continue at a shallow temperature without a single barrier on the engine parts.

Main features and benefits to using:


The requirements of this oil include Detroit Diesel, Caterpillar, Navistar, Cummins, Volvo, and Mack. Its designation ensures to protect all the utility, heavy-duty, and pickup diesel engines. And beyond question, Valvoline will support you by its service on and off highways.

Full Synthetic

Here, the compounds of this oil are fully synthetic and thus make the frictions of engine parts as little as possible. And the deposits will not appear on your engine because of this oil’s refinement and molecular size.

Thermal properties

With the help of thermal properties, Valvoline gives safe and faster starts in freezing weather. And, also the oil controls heat fluctuations and other hot weather operations.

Improved fuel economy

Because of the improved fuel economy, this product does not require that much gas to go through a distance.

Oxidation resistant

Valvoline Premium is an excellent oil since it is improving crucially in oxidation resistance. By this action, it can retain the properties of the engine and enhance its life.

Wear protection

After a specific use of this oil, you will notice wear protection in your engine, reducing the friction. Heavy-duty equipment and trucks perform exceptionally well when they get lubrication of this oil.


  • Ingredients: Full Synthetic
  • Viscosity: 5w40
  • API SP/SN PLUS/SN: Does not meet
  • GM dexos1® Gen 2*: Does not Meet
  • Vehicle service type: Truck
  • Liquid volume: 12 Quarts


  • It can provide extreme performance to any diesel engine. And in the meantime, it does protect vehicles when they are in modern treatments and emissions.
  • Best for those engines with Diesel Particulate Filters (PDF) and Exhaust Gas Recirculation (EGR).
  • Has premium lubricant properties
  • Supports throughout giving temperature resistance
  • Works well even in the longer chain intervals and makes it easy for the vehicles to engage in better performance.
  • Makes sure that the engine operates at a lower temperature
  • Safeguards the engines when oil oxidation appears as the main problem


  • Sometimes the sealing attributes with certain complications
  • An expensive one compared to other synthetic oils

#4. Delo 400 SDE SAE 15W-40 Motor Oil

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Delo 400 SDE SAE 15W-40 comes up with advanced technology of ISOSYN and mixed fleets. You can use it for four-stroke gasoline engines and turbocharged four-stroke diesel engines, expecting the best results.

Moreover, this oil fulfills the requirements of engine performance and industry manufacturers with its super-premium quality.

The formulation of Delo 400 aids heavy-duty engines so well that they leave no stone unturned to process thrillingly. As a perfect oil, you can choose this product because it complies with all diesel engines. 

Main features and benefits to using:

Lower CO2 emissions

There are a lot of difficulties we find, usually due to higher CO2 emissions. But once you grab this oil for your car, such kinds of emissions will reduce chronologically.


By meeting the API SP standards, this oil provides sheer protection to engines against Low-Speed Pre-Ignition along with Timing Chain. It follows that your engine will have a long-lasting life throughout.

Fewer operation costs

The best thing about Delo 400 is, it needs minimal maintenance. In addition, since the oil will protect your engine for a long time, you will not have to bear the extra operational costs as well.


  • Viscosity: 15w40
  • API SP/SN: Meets
  • GM dexos1® Gen 2*: Does not meet
  • Liquid volume: 1 Gallon


  • It is ideal for four-stroke gasoline engines and turbocharged four-stroke diesel engines
  • Fulfills the requirements of engine performance and industry manufacturers
  • Conveys lower emissions of CO2 gas
  • Ensures a long-lasting performance of engines


  • Grants complex lubrication sometimes

#5. Shell Rotella T6 Full Synthetic 15W-40 Diesel Engine Oil

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Shell Rotella stands up when it comes to one of the best synthetic diesel oil. The designation of this product makes sure that the performance of engines uplifts and maintains the quality for a long time.

Moreover, the heavy-duty engines with low emissions will work outstanding once they get lubrication of Shell Rotella T6.

This oil is an exceptional preference for the general haul, on-highway fleets, public-transport operators, agriculture, construction, and diesel pickup trucks.

Main features and benefits:

Fuel economy

Here, you will get a 1.5% improved fuel economy than other SAE 15w40 oils.

Triple protection

With the triple protection formula, Shell Rotella grants fully synthetic-based oils where you will get advanced additives. And this availability gives protection that your engine will stay energetic with a long life.

Additive technology

You will not have to strain from now on because of the dirt, soothes, and other contaminants that appear primarily on engines. As the additive technology of this oil stands like a barrier to those problems, your engine will operate smoothly for sure.


  • Ingredients: Full Synthetic
  • Viscosity: 15w40
  • API SP/SN PLUS/SN: Meets
  • Liquid Volume: 128 Fluid Ounces


  • Makes sure that the performance of engines uplifts
  • Best for heavy-duty engines with low emissions
  • An exceptional preference for the general haul, on-highway fleets, public-transport operators, agriculture, construction, and diesel pickup trucks
  • Kees away dirt soothes, and contaminants from engines
  • Helps to run vehicles smoothly in a long route


  • The jug of this oil is not so good

#6. Cummins 3265336 Onan SAE 15W-40 oil

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Do you want to give your motorhome a splendid alternative that can raise it with better performance? Then Cummins Onan 15w40 oil has just got you covered. As an Onan generator, this oil makes sure that you get no signs of leakage or broken seals on the jug.

Here, the mileage equates to operational hours and serves through utmost reliability. Most of the generators seek Cummins Onan because of its astounding lubrication and smooth use.

Let’s just not beat around the bush anymore and get straight to the point by gazing at some of its key features.

Main features and benefits:

Goes to the fill line

Many oils usually overfill the generators. But that’s not the case after you pick Cummin’s oil for your generator.

Sludge protection

Sludge and deposits create a massive problem in engines and generators. And lately, it seems impossible to find the right oil to remove those problems. For this reason, Cummins Onan oil has come out to protect your engine with its best cleaning power and eliminate all sludge.


  • Viscosity: 15w40
  • API SP/SN PLUS/SN: Does not meet
  • ILSAC GF-6: Does not meet
  • Liquid volume: 32 Fluid Ounces


  • A splendid alternative for motor homes
  • Gives no signs of leakage or broken seals
  • Serves through utmost reliability
  • Goes to the fill-line and lubricates properly
  • Removes sludge and deposit problems in a click


  • Not an affordable oil

#7. Quaker State Motor Oil

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Quaker State 10W-40 is one of the main priorities for vehicle owners, especially for its optimal protection. Be it high-speed operation or repetitive; this oil summons the best performance every time. Also, you will get satisfactory maintenance of viscosity from start to end, even in stop-and-go driving.

Are you looking for optimal protection in your engine? Then Quaker State is the particular one you can have. This oil not only removes rust from engines but also gives durable wear protection.

Main features and benefits to using:


Quaker State 10w40 meets the requirements of industry specifications, like- API SN and other categories. So, if you grab this oil, it’s certain that you will have after-treatment compatibility, better seal compatibility, better sludge control, and so on.

Ergonomic design

To increase productivity, Quaker State uses an ergonomic design in this product so that you apply it more comfortably.

Dampen shock

Quaker State motor oil blows all the mechanical shocks of the engine, absorbing the engine strikes. Also, it will reduce the opposing forces and resist rupture with its vital lubricant.


  • Ingredients: Full Synthetic
  • Viscosity: 10w40
  • API SP/SN PLUS/SN: Meets
  • Vehicle service type: Car
  • Liquid volume: 160 fluid ounces


  • Protects the engine from harmful acids and thus removes corrosions
  • Maintains viscosity throughout and provides optimal protection
  • Eliminates sludge and deposits from vehicles
  • Makes sure that the engine gets durable wear protection


  • Not a good option for new brand vehicles

#8. Mobil 1 5W-40 Turbo Diesel Truck Synthetic Motor Oil

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Mobil 1 5w40 is an excellent alternative for diesel trucks and engines, as it comes from crude oil. Hence, you will get a high density of energy and an acton-packed performance in your fuel cars.

The primary purpose of this oil is to clean, lubricate, and excellent engines within a blend of conventional and synthetic. You can add it to your refining process for both hot and cold weather conditions.

Features and benefits to using:


The best thing about Mobil 1 5w40 oil is that it can quickly adapt to any vehicle. Such as trucks, cars, motorcycles, farm equipment, ATVs, and many more.

Extended drain interval

You will not have to worry about the friction problems that usually crop up on engines because this oil is competent enough to fight those frictions and prevent future oil leaks. As a result, you will get an extended drain interval of about 1500 miles.

Powerful energy

Most of the time, we fret thinking about inadequate compliance that some conventional oil owns. But Mobil 1 will keep your engine out of such problems as it gains powerful energy resources. And it will also maintain the viscosity as you expect from any high-quality motor oil.


  • Ingredients: Conventional and Synthetic
  • Viscosity: 5w40
  • Vehicle service type: trucks
  • Liquid volume: 5676 Milliliters


  • An excellent alternative for diesel trucks and engines
  • Gives a high density of energy and action-packed performance in fuel cars
  • Adapts with all types of vehicles easily
  • Fights against frictions and prevents the future oil leaks
  • Gains a powerful energy resource and makes sure to maintain the viscosity


  • Requires an extra cost for maintenance

Buying Guide for Cummins 6.7

Enhanced friction durability assures smooth shifting of gear

The smooth-shifting capacity of your car depends on friction. To enhance the conflict, release the clutch slowly and press on the accelerator. After moving the gear shift, you have to remove your left foot from the grip. You need to apply pressure on the accelerator pedal gently.

There is a proverb that says practice makes a man perfect. So, you’ve to practice more to shift gears smoothly. Transmission fluid also works to change the engine’s gear. Its enhanced friction durability assures smooth shifting of equipment.

These fluids also help you to drive safely in both city and highway driving. Again, the oxidation resistance helps avoid viscosity increases. It will degrade transmission performance and service life.

Protects against copper corrosion and rusting

Copper is considered a noble metal in the world of the electronic industry. It resists the attack of oxygen. Reduce some air pollutants such as Hydrogen Sulphide. This element does unevenly change the surface properties.

The layer of hydrogen sulfide is forming a thin layer inside the engine. On the other hand, the corrosion of Cu happens when the water gets in contact with some bare metal.

 If your car dissolves with adjacent pieces of metals are of different voltages. Galvanic corrosion in joints is also responsible for copper corrosion. So, the right oil will help you to prevent copper corrosion and rusting.

Improved oxidation resistance

Some cars also have faced trouble with oxidation resistance. Oxidation resistance is an active reaction of metal and oxygen. It becomes more effective at a high temperature. There is a chance to oxidize your metallic elements with oxygen in the air. The car heat also accelerates oxidation.

Best Oil For Cummins 6.7

You may be thankful for the car oil as it has improved this problem manually. We can slow the process of oxidation through synthetic-based oil. Most of the synthetic crude provides inherent heat. And it also helps to reduce oxidation stability to conventional unsaturated fats.

Prevent deposits and sludge buildup

Car oil also helps to prevent deposits and sludge buildup. But some motor oil is not immune to oxidation. As oil creates a reaction against oxygen, you may face the problem of deposits and sludge buildup. If this chemical change continues, the oil molecules will lose one or more electrons.

These chemical changes were causing so many defects inside your car. With the formation of sludge and deposits, your engine loses its efficiency. It also increases the risk of engine failure. So, synthetic oil will prevent these defects additionally.

Excellent internal engine heat protection

The right oil is an excellent tool for minimizing engine heat. The excessive heat of your engine may cause damage to your car. Motor oil can last longer than your engine life.

Despite engine heat and stress, some motor oil keeps your engine cleaner and more efficient. No mention that engine oil will save your money in the long run through precise maintenance.

Low-temperature protection

Before buying any engine oil, you must know the product that gives your car low-heat protection. Low-temperature protection is a must because your engine needs cold start protection on a short drive. Mobil synthetic oil is a good protector in that matter.

Most of the driving consists of short journeys such as quick trips, bringing your son from school and down to the shop. In that case, your engine hardly had time for warmth before you turned it off again. Experts suggested choosing any engine oil. The expertise has proven that it will flow freely at low temperatures such as 40-50⁰C.

Extended drain interval

Many car drivers still mention that the motor oil should change once every 400-500 miles. Vehicle or car manufacturers added two oil change intervals—one manufacturer measured in miles, and another estimated in months.

Extended drain interval is a reducer of oils and filter changes. A good Mobil will have an extended drain interval that you won’t need to change after a while. It also allows a more significant time between having to change the motor oil and filter.

Many car owners recommend OEM intervals. The OEM interval allows you to change the oil after 4,000 hours if you added mineral water. You’ll get better results while using synthetic oil. It will give you 8,000 hours of backup in a long trip.

Reduces engine deposits

A good mobile phone also reduces engine deposits. In both new and old engines, you’ll find a common fault that is harmful deposits. These occur from impurities in gasoline or dust. The problem you may felt like this,

  • lower gas mileage on engine,
  • poor acceleration and lost power of fuel,
  • hardly start,
  • auto ignition trouble like knock and ping,
  • increased the exhaust emissions, etc.

One tank of oil can clean all these entire problems of your hemi. It also helps to optimize engine oil.

 Fast start-up in cold weather

Some users complain about their hard start during winter. It often happens at low temperatures, and the engine gets stuck on fuel and burns. Engine oil is a must to avoid this situation. It will increase the machine in a vulgar atmosphere. Your engine gets started faster than previous.

Ultimate cleaning power

Some fuel oil also has ultimate cleaning power. Your dirty engine may drain, and you should replace it. You can check out these below signs to examine if your engine needs cleaning detergent or not,

  • If your car oil has been coming off,
  • If engine oil not changed regularly,
  • If you feel sludge build up in the oil cap.

Your hemi may not feel like this problem if you choose the right oil.

Cools down the engine

Your engine stays at a medium temperature for the cooling systems. The engineers of the manufacturer usually set the vehicle temperature. The engine runs itself at a lower temperature than the oil.

The heat transfer occurs from the oil for cooling the parts of the engine. Cooling down your machine is a must to increase stability. But overfilling the engine with oil isn’t too good. A sufficient amount is enough to cool down the engine.

Increases fuel economy

The cost of motor fuel is increasing day by day. A right or sufficient oil will give you more relaxation in this regard. An engine oil increases your fuel economy by its ingredients.

Diesel oil can increase the risk of engine emissions in factors like organic carbon, viscosity modifiers, high molecular mass polymers, etc. Those can affect the car fuel capacitors and affect fuel economy.

Fights friction and prevent future oil leaks

Perfect engine oil will fight against friction and prevent future oil leaks. They must design to stop and seal leaks caused by primary problems. High-quality oil reduces this trouble and treats the head gaskets to regain their flexibility.

Oil leaks are often inadequate for the environment. Constantly changing your oil may hit the performance of your engine. You should purchase oil that can perform well in those regards.

Antioxidants prevent oil breakdown

Engine oil also acts as an antioxidant for preventing oil breakdown. Antioxidants are an agent to prolong the life of a lubricant inside the engine. It increases the oxidative resistance of the oil.

In a word, antioxidants allow the engine to have more fat to operate the car in higher temperatures. Otherwise, it won’t be possible to drive a car without them.


Hopefully, you could snap your most eminent oil from the above-given products. Here, all the items convey the top-leading brands with commendable features where no consumers have any objection.

To minimize your option a little more, I suggest giving a second thought to Shell Rotella and Valvoline’s oil. Since they are merging highly in the market, you can select one of them.

But ultimately, all that requires is to choose wisely according to your preference. And lastly, give a pleasant experience to your vehicle with perfect oil.

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