What is the best oil for duramax diesel egnines

Best Oil for Duramax Diesel Engines [FAQs, Top Picks & More]

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DMAX produces the Duramax V8 engine, which is a series of 6.6-liter Diesel V8 engines. The 6.6L Duramax has been in manufacturing since 2001 and it has shown to be a rather dependable and robust engine across the board. While several variants of the engine have appeared throughout the years, all Duramax generations are built to the same standard.

Just like every other engine, the Duramax needs good oil to operate at its peak. A good engine oil protects all of the working components and prevents them from grinding against each other. Metal-on-metal friction would quickly ruin any engine if it weren’t for the protection provided by using the right oil.

Here in this article, we have compiled information on the five best oils for your Duramax diesel engine to ensure that it runs smoothly and effectively. So, without any further ado, let’s start with the list.

Top 5: Best Oil for Duramax

After carefully going through a number of oils available for Duramax engines, we have shortlisted the five best products. The selection of these products was based on very strict criteria to ensure that every oil offers the best service and keeps up to its word of running the car engine smoothly and effectively while not being a burden on our pocket.

In short, every product listed here offers the best value for money. Further, you can find all the information you need about these five oils for your Duramax, which will help you make an informed decision regarding which product will work best for you.

1. Royal Purple Diesel Engine Oil 15W-40

Royal Purple motor oil is a high-performance synthetic lubricant that promotes an increase in engine efficiency. This engine oil is advertised as being able to significantly increase fuel efficiency.

Royal Purple makes it easier to start your car, particularly on chilly days. It is able to do this because during start-up, it flows quickly to grease the engine components and decreases friction throughout the entire engine.

This Royal Purple oil also helps clean your engine with sophisticated synthetic solvency. With their 1 Oil Change Pledge, you may enjoy the ease and convenience of prolonging your oil change frequencies on your cars.


  • Royal Purple Diesel Engine oil’s premium base oils are combined with unique additives to generate high-performance motor oils that improve vehicle dynamics as well as corrosion resistance.
  • At all temperature ranges, high-quality synthetic base oils guarantee outstanding cold flow and preservation.
  • The viscosity of this engine oil is 15W-40.
  • It’s labeled as a universally fit engine oil.
  • This is a good option for engines that define API service; CI-4, CI-4 Plus, CJ-4, and CK-4.


  • The additives in this complete synthetic oil assist in keeping the oil clean for extended periods by cleaning up the filth burnt up in the cylinders.
  • It helps the engine to run much more smoothly than ever before.
  • It has the capacity to increase the time between oil drains substantially.


  • There are no indicators on the bottle to assist you in figuring out how much you’ve poured in.
  • It is labeled as a high-end product, and thus is more expensive


2. Mobil Super Delvac 1300 Diesel Engine Oil 15W-40

This oil from Mobil is one of the most effective synthetic oils in the market. It’s praised for its effectiveness and long-term engine dependability. The SuperSyn Technology in the Mobil 1 ensures the right amount of resistance.

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For generations, it has been the factory-fill preference for high-performance engines. Furthermore, Mobil 1 provides an oil change frequency of up to 15,000 miles, rendering it extremely cost-effective.

Likewise, Mobil Delvac is a high-performance diesel engine oil that provides great lubrication for today’s modern diesel engines, allowing them to last longer. As a consequence, almost all major European and American engine manufacturer’s standards are met or exceeded by this product.


  • The weight of this oil is SAE 15W-40
  • The Mobil Delvac 1300 Super is the product of significant collaborative development and testing with major OEMs and is suitable for a broad variety of heavy-duty applications and operating situations.
  • It has exceptional cold starting and oil pumping characteristics at low temperatures.
  • It’s a high-performance diesel engine oil that assists in extending engine life in the harshest on and off-highway environments while offering exceptional effectiveness in contemporary, high-output, low-emission engines, even those with EGR (Exhaust Gas Recirculation).
  • They meet and otherwise surpass API service classifications; CJ-4, CI-4 PLUS, and CH-4, as well as essential Original Equipment Manufacturer (OEM) criteria for 2007 engines.
  • The Mobil Delvac 1300 Super is fully backward compliant and will offer the same outstanding effectiveness with previous traditional engines.


  • It arrives in a compact and extremely secure package, unlike many other engine oils. This prevents it from leaking and being wasted.
  • This engine oil ensures a smoother and cleaner engine with long intervals between oil changes.
  • This motor oil has the advised quantity in its bottles.


  • Some people have reported being dissatisfied with this products performance

3. Shell Rotella T6 Synthetic Diesel Engine Oil Blend 5W-40

Shell isn’t just some other brand of motor oil; it’s a cut above the others in terms of performance. Since it’s a contemporary synthetic product produced from natural gas, it acts as a protective barrier against corrosion. This is why it is more stable at the molecular level than crude oil-based products.

Shell Rotella is a renowned performer that may be used in a variety of heavy-duty engine configurations. Shell Rotella is a fully synthetic oil for diesel engines, and it’s perhaps one of the finest when you consider its fair price.


  • Shell Rotella T6 5W-40 diesel engine oil is a blended synthetic motor oil with proprietary Triple Protection Plus technology that protects from corrosion, contaminants, as well as oil degradation.
  • It is created using blended synthetic base oils and sophisticated compounds.
  • It also offers improved low-temperature circulation and improved fuel efficiency without sacrificing endurance.
  • Shell Rotella T6 5W-40 Blended Synthetic motor oil is suited for nearly all current low-emission heavy-duty engines and previous diesel engines that require a lot of effort.
  • It is a good choice for on-highway fleets, general haul, including trucks, with a comprehensive range of specifications and certifications from many of the world’s major engine manufacturers.
  • Compared to other 15W-40 lubricants, Rotella provides a 1.5% increase in fuel economy without affecting engine safety or dependability.
  • When equated to previous generation API CJ-4 engine oils, it offers considerably more security against detrimental engine wear.


  • It’s available at extremely reasonable prices compared to other 5w40 oils for the Duramax engine.
  • Shell Rotella T6 blended synthetic heavy-duty engine oil prevents viscosity degradation.


  • The packaging is not good as others, and some buyers reported that their oil bottles came leaking.

4. Amsoil Heavy-Duty Diesel and Marine Engine Oil 15W-40

Amsoil makes the best diesel oils within the industry, protecting your hardworking diesel engine and managing to keep your vehicle working on the road for longer.

Furthermore, Amsoil synthetic motor oil survives high heat and shear stress pressures, surpassing competitive products and industry requirements.

For optimum protection, it lives up to the destructive impacts of high-horsepower, contemporary engines. Amsoil synthetic oil is somewhat more pricey than other synthetic and traditional lubricants, but it is well worth the investment because it improves the efficiency and security of your engine.

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  • Drainage frequencies for Amsoil Synthetic Heavy-Duty Diesel Oil are considerably longer than those suggested for traditional petroleum lubricants.
  • Its long-drain compound chemistry and innovative synthetic formulation provide optimal engine preservation, cleansing, and effectiveness over longer drain intervals, lowering vehicle maintenance and waste-oil disposal expenses.
  • It’s been reinforced with cleanser and dispersion ingredients and is inherently soot-resistant. Its purpose is to keep soot particles apart and keep them from accumulating into bigger, wear-causing particles.
  • Its volatility is lower than that of ordinary petroleum oils. Because fewer vapors enter the combustion chamber, oil consumption and pollutants are reduced. AMSOIL 15W-40 Diesel Oil has lower volatility, which helps it keep its viscosity after high-temperature use for long-term durability.
  • The viscosity of this engine oil is 15W-40.


  • It is available at extremely reasonable rates as compared to other engine oils of the same viscosity.
  • This is a self-cleaning engine oil that keeps your engine free of debris.
  • Longer drain intervals between oil changes, making it cost-effective.


  • It is not always considered to be the most suitable engine oil for new Duramax engines.

5. Shell Rotella Full Synthetic T6 Diesel Engine Oil

We have added yet another Shell T6 diesel oil to our list due to the number of benefits it has to offer at an extremely reasonable price.

Another reason for adding another Shell engine oil with the same viscosity, is the difference in synthetic features of both. While the previous option is a synthetic blend, this one is a fully synthetic oil.

Full synthetic oil is made out of a synthetic base stock combined with a range of additives that improve the oil’s performance.


  • The viscosity grade 5W-40 is ideal for starts in both cold and hot conditions.
  • In heavy-duty diesel engines, new multi-functional dispersion additives combined with synthetic base oils give better protection against ash, grime, as well as other pollutants.
  • Shell Rotella T6 full synthetic heavy-duty engine oil prevents heat degradation, giving you peace of mind during your maintenance window.
  • This engine oil prevents viscosity decrease due to shearing and keeps your heavy-duty diesel engine running at peak performance.
  • The manufacturer’s shear stability test guarantees that there is no viscosity loss and that the oil pressure remains consistent all through its useful lifetime. As a result, your engine will be protected for a long period.
  • It provides a 1.5% increase in fuel economy without affecting engine stability or endurance.


  • It will maintain viscosity over a wide temperature range, ensuring that the engine runs smoothly and that the oil does not lose viscosity often.
  • It outperforms other oils of the same viscosity in terms of fuel efficiency and engine performance


  • This oil is more expensive than a few other alternatives available in the market.

Oil for Duramax Diesel Engines – Consider these Important Factors

buying guide for the best oil for a duramax diesel engine

In this article above, we have explained in-depth five of the best oils available in the market for your Duramax truck engine. However, one question that might arise in your mind is how to determine which oil will work best for your specific situation. For this purpose, keep reading further.

The manufacturer recommends a certain type of oil, grade, viscosity, and other specifications for each diesel engine. These tips are essential for keeping your engine in good shape and functioning over a long period. In order to avoid issues, you should also follow these guidelines.

Following are the factors that you can look out for when finalizing which oil to buy for your Duramax.

1. Type of Oil

Synthetic oils for Duramax diesel engines are currently recommended by almost all manufacturers. However, there are distinct types of synthetic engine oil.

The formulation of fully synthetic oils is completely pure. There is no added conventional oil. Synthetic blends, on the other hand, incorporate a variety of oils.

2. Viscosity of the oil

The most crucial aspect to consider while choosing an engine oil. The temperature has a significant impact on oil efficiency. Its impact is measured by the viscosity rating.

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Multi-grade oils are used in all of the common formulas. As a result, the fluid is effective all year. The 15W-40 grade engine oils are highly recommended by manufacturers.

They work well in hot, average, and somewhat cold climates. When the ambient temperature is 0°F or above, 15W-40 is recommended.

For a clear understanding:

  • 5W-40: For moderately cold to severely cold climates. This viscosity level allows the oil to flow without freezing. The engine starts immediately. In high temperatures, however, it loses performance.
  • 15W-40: For all-purpose usage, excellent in both hot and cold weather. It maintains a sufficient viscosity at extremely high temperatures.

3. Specification of Oil

The oil must meet engine specifications first and foremost. Specific oil may be required for certain Duramax engines. It’s a typical occurrence with older automobiles. You may learn more about this aspect by reading the feature descriptions of each of the products listed above.

4. Composition of the Oil

Any high quality oil composition must have injected additives. The compounds have certain advantageous properties. The additives improve the performance and efficiency of internal engine components.

The liquid used should be resistant to wear, corrosion, deposits, and accumulation. Engines that are kept clean have a longer lifespan and are more serviceable.

Frequently Asked Questions

1. What oil capacity do Duramax engines have?

For most Duramax engines, the oil capacity scarcely differs. With the filter, the capacity is 10 quarts or 9.5 liters. However, without any filter replacement, it may reach 9.2 quarts or 8.7 liters.

2. How often should you change the oil?

The interval is, in fact, determined by the vehicle’s specific model. The suggested interval for most Duramax engines is between 5000 and 7000 miles. Before hitting 7500 miles, or at least once a year, change the oil. On the other hand, a good grade oil may last for over 10,000 miles in a well-maintained engine.

3. What is the oil pressure in the Duramax at standby?

The operating pressure of Duramax engines is determined by vehicle specifications. However, the typical range of functional oil pressure is 14 to 42 psi. Also, to add to that, it’s 14 psi when it’s idle and hot.

4. How to do an oil change for the Duramax diesel engine?

You can do it the same way you would for any other situation where you need to change the oil on a large vehicle.

If you would prefer some guidance, you can check out a guided video and follow their official instructions.  Diesel Hub has also put out a great guide going over the steps required to change the oil on a Duramax Engine.

Just make sure you’re using the right Duramax oil, as indicated in the above buyers guide (the importance of using the correct viscosity can not be understated).

That’s all there is to it! You should be fine to go at this point as long as you make sure you’re using the right viscosity.

List of Engine Oil by Vehicle:


Engine oil is probably the most important product to help with the smooth operation of your car or truck. Maintaining the general serviceability of vehicle engines necessitates the use of high-quality oil.

A decent formula can ensure that engines performance is optimal. And the finest oil for Duramax diesel engines can provide a fantastic performance boost.

In this article, we have explained in detail the oil requirements of a Duramax diesel engine and how you can ensure that the engine oil you choose will work best for you. Apart from that, we have also listed down five of the best engines oils you can find for your Duramax engine. We listed their features in detail, accompanied by pros and cons, to help you understand more about the product and assess it. All of this was done to ensure that you eventually make an informed decision.

We hope after reading this article that you thoroughly understand the engine oil requirements for your duramax, and we hope this article has made selecting the best oil a little easier for you.

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