Best Oil for Duramax: Top 5 for 2021

The best oil for Duramax engines doesn’t just give you the satisfaction of a smooth-running motor, it also ensures that your engine will last a long time.

Duramax engines are highly efficient and reliable, generating high levels of energy to power your vehicle. In order for the engine to achieve such power, it needs sufficient heavy-duty and highly reliable oil.

This will ensure the engine runs smoothly and works perfectly. The best oil doesn’t just give you the satisfaction of a smooth-running motor but it also guarantees your Duramax engine is protected and should last a long time.

Best Oil for Duramax

The right oil should be high-quality and enough to generate high torque and horsepower. It is imperative you find good engine oil, especially if you do regular long-distance journeys. Finding the right engine oil for your Duramax engine can be a hassle!

For high-powered Duramax engines, we have listed the highest-quality oils to ensure your motor runs at full capacity. Our in-depth reviews will help you decide what the best choice is for your engine’s functionality.

With several options, we have also included a helpful buyer’s guide with factors to consider when buying top-quality oil. Our FAQs section will answer the most common queries that you may also have.

In a hurry? Let’s take a look at our top choice!

5 Best Oil for Duramax

1. Shell Rotella T6 Synthetic Heavy Duty Engine Oil

Shell Rotella T6 Full Synthetic 5W-40 Diesel Engine Oil (1-Gallon, Single Pack, Old Packaging)

Shell Rotella T6 Synthetic Heavy Duty Engine Oil is a fantastic supportive solution for your Duramax engine.

Its main job is to encourage your engine’s output and this is exactly what it does. This exclusive low-ash formula offers outstanding engine compatibility containing additives for the best performance possible.

It has a built-in Triple protection Plus which promotes a safe engine startup. It is important to find an oil that can withstand varying adverse temperatures or climates.

Shell’s T6 engine oil offers superb efficiency whatever the conditions you are in. Its fully synthetic base imparts improve the burning of fuel within your engine so you shouldn’t have to experience any oil breakdowns or wear.

Shell Rotella T6 Synthetic Heavy Duty engine oil offers enhanced fuel economy capabilities. It does so without any risk to the engine’s durability.

Your Duramax engine will benefit from the improved deposit control this oil has to offer to help your vehicle run smoother for longer.

Good supportive solution – Its low-ash formula will help the car’s fuel efficiencyPoorly packaged in some cases resulting in a damaged container
Gives excellent engine durability – Improved deposit controls enhance your engine’s protection
Offers consistent optimal pressure – Tackles inner heat throughout its service interval
Maximizes engine functionality – Fully synthetic base imparts improve the burning of fuel inside your engine
Enhances fuel efficiency – Will save you money on fuel in the long run
Shell Rotella T6 Full Synthetic 5W-40 Diesel Engine Oil (1-Gallon, Single Pack, Old Packaging)
  • For best performance, follow the manufacturer's recommendations in your vehicle owner’s manual.
  • Better fuel economy - compared to 15W-40 oils Rotella offers enhanced fuel economy capability of 1.5% without compromising engine protection or durability
  • Improved wear performance - provides a significantly increased level of protection against harmful engine wear when compared to previous generation API CJ-4 engine oils
  • Improved deposit control - advanced multi-functional dispersant additives in combination with synthetic base oils provide an enhanced level of protection against the effects of soot, dirt and other contaminants
  • Emissions system compatibility - advanced low-ash formulation helps control blocking of or poisoning of exhaust after-treatment devices, helping maintain vehicle emission compliance and engine fuel efficiency

2. Liqui Moly Synthoil Premium 5W-40 Synthetic Motor Oil

LIQUI MOLY Synthoil Premium SAE 5W-40 | 5 L | Synthesis technology motor oil | SKU: 2041

Next up is a synthetic oil from the renowned German brand Liqui Moly. This oil will work well in any diesel or gasoline engine.

It is primarily made for engines with more modern-technologies such as a multi-valve, supercharging, and timing configuration.

If you live in a cold climate, this Liqui Moly motor oil will work straight away. Its cold-cranking abilities help will lubricate the entirety of your Duramax engine for optimal performance in all weather conditions, especially at colder temperatures.

If you frequently drive with heavy loads, year in, year out, your Duramax engine will be crying out for quality heavy duty oil. This motor oil will be the savior allowing your engine to reach its peak potential while improving the overall fuel efficiency.

This oil will also keep clean, removing any contaminants from within the engine, allowing your motor to run smoothly and efficiently. Unwanted sludge or soot deposits will be eliminated with the use of Liqui Moly motor oil improving your engine’s efficiency.

Fuel efficient – helps save fuel over long periods of timeBlue container can be confused with different grades of oil
Ideal in cold temperatures – Lubricates your engine on a cold start in order for your engine to run smoothly
Works very well with upgraded engines – Perfect for vehicles with more modern technologies that may require more specific oils
Improves motor’s overall performance – Keeps your engine free of any contaminants and deposit build-ups
Ideal for diesel and gas – Suitable for gas and diesel engines, especially modern vehicles
LIQUI MOLY Synthoil Premium SAE 5W-40 | 5 L | Synthesis technology motor oil | SKU: 2041
  • Superior performance and long engine life in gasoline and diesel vehicles
  • Instant lubrication after cold start
  • Instant lubrication after cold start
  • Keeps engine clean
  • For extended service intervals

3. Shell Rotella T4 Triple Protection Conventional Engine Oil

Shell Rotella T4 Triple Protection Conventional 15W-40 Diesel Engine Oil (2.5-Gallon, Single)(Packaging may vary)

In at number three is another entry from Shell. This is a new and improved version of its original predecessor.

Shell Rotella T4 Triple Protection Engine oil has been upgraded in order to adapt to any engine’s condition. These include old diesel engines and more modern low-emission engine models.

Your engine will be fully protected thanks to Shell’s impressive protection technology which removes deposits and reduces wear. It will prevent soot build-up as well as other contaminants, resulting in a more efficient, eco-friendly engine.

This oil has 50% resistance against oxidation so it will run for longer even when the engine is at maximum output. Your Duramax engine will be fully protected thanks to the oil’s acid control. 

With a variety of emission systems around, it is good to know that Shell Rotella T4 engine oil is compatible with many of these. Your engine should perform much better with this oil, even when under extreme pressure.

Has superb wear protection – New protection technology reduces wear and removes harmful build-ups in the enginePackaging can be poor leading to leakage in transit
Helps your engine perform well at all times – Even under stress and high temperatures, this oil helps your engine perform to its full potential
Prolongs engine life – Its acid control will keep your engine running for longer
Less ash content – Formulated with less ash content protecting the exhaust catalyst
Compatible with many vehicles – Suitable for old diesel engines and those with modern-technologies as well as a host of emission systems
Shell Rotella T4 Triple Protection Conventional 15W-40 Diesel Engine Oil (2.5-Gallon, Single)(Packaging may vary)
  • For best performance, follow the manufacturer's recommendations in your vehicle owner’s manual.
  • Formulated for enhanced deposit protection to help keep engines cleaner over the oil drain interval
  • Exclusive low ash formulation helps protect the exhaust catalysts and particulate filters found on the latest low emission vehicles
  • Meets or exceeds API CJ-4 requirements, and is designed to provide extra performance Shell Rotella T4 performs well in both older and new engines
  • Enhanced shear stability performance for viscosity control and optimal oil pressure in your engine

4. Delo XLE 400 Synthetic Blend Oil, 15W40

Delo 400 XLE Heavy Duty Synblend Diesel Engine Oil 15W-40, 1 Gallon, Pack of 1

If your Duramax is used for heavy loading or long journeys with heavy loads, Delo XLE 400 Synthetic Blend oil may be the best option for you.

Your hard-working engine should feel the benefits of this heavy-duty oil pretty quickly as it lubricates and cleans the entire engine prolonging its lifespan.

There are some impressive cleaning additives with this oil that can cut your maintenance costs exponentially. Any soot build-up or dreaded rust can be easily handled by Delo XLE oil ensuring no harm comes to your engine.

If you drive on the highways often, the ISOSYN Advanced Technology in this oil will work a treat! It is made to generate low greenhouse gas emissions and is compatible with Diesel Particulate Filter (DPF) and selective catalytic reduction (SCR).

Its long drain ability is outstanding ensuring you get the best performance with both off and on-road engines. With so many great features, this is an exceptional choice of oil, especially in its price range.

Very high-quality synthetic-blend oil – Provides protection and support for your engine’s overall performanceThe container’s handle is poorly designed – Makes pouring the oi out a little difficult 
Excellent soot dispersant – Lubricates and cleans your engine, removing soot build-up or rust
Superb wear protection – Ideal for vehicles that are used regularly for long distances, protecting the engine from possible wear and tear
Perfect for heavy loads – Will help your engine run smoothly and efficiently with heavy loads over long distances
Delo 400 XLE Heavy Duty Synblend Diesel Engine Oil 15W-40, 1 Gallon, Pack of 1
  • A premium synthetic blend, long drain mixed-fleet engine oil specifically formulated for on- highway applications, including 2017 greenhouse gas (GHG 17) compliant diesel engines
  • Isosyn Advanced Technology: The Next Generation of Heavy Duty Engine Oil Chemistry - engineered to deliver longer oil life, better wear protection and longer engine life
  • Isoclean: Certified clean - ensure your lubricants meet OEM cleanliness requirements to help you minimize downtime, reduce maintenance costs and extend equipment life
  • Provides high performance piston deposit control and turbocharger protection due to its superb oxidation performance. Its high performing detergent and dispersant additives provide excellent diesel engine component protection.
  • Exceptional soot dispersancy and wear control - Cylinders, pistons, rings, and valve train components are well protected against wear and corrosion, providing optimum service life and minimal maintenance, contributing to maximum equipment utilization and minimal downtime.

5. Valvoline Premium 5W-40 Oil, Full Synthetic Engine

Valvoline Premium Blue Extreme SAE 5W-40 Full Synthetic Diesel Engine Oil 1 GA, Case of 3

Valvoline provides top-quality premium engine oil time and time again. This premium 5W-40 oil is another example of the brand’s quality helping protect your engine’s components from soot, debris, deposits, and wear.

If you experience classical seasons (cold and hot), Valvoline Premium engine oil will be able to tackle these temperatures easily. You will be safe in the knowledge that no problems should occur with your engine because of a change in temperature.

Your engine will thank you for using this oil by running faster and better, whatever the weather conditions! Its high total base number (TBN) helps tackle acidic materials and unwanted contaminants in your engine. It does this by cleaning out your engine for optimal and increased performance.

Your wallet should stay fuller too with this oil as it helps improve your fuel economy as well as reduce any ecological footprints.

The chances of oxidation of your engine will be cut with the use of Valvoline Premium oil so your vehicle can perform better in standard or long-distance journeys. If your engine is modern such as an Exhaust Gas Recirculation or DPF, this oil will work well.

Protects against wear, soot, and deposits – Formula will lubricate your engine and remove unwanted debris withinSeal is a little weak under the caps of the containers
Recommended by leading engine manufacturers – Very reliable oil according to experts for top results
Compatible with modern engines – Works for older engines as well as modern vehicles that may require a specific type of oil
Improves fuel economy – This will help you save money with better fuel efficiency overall
Valvoline Premium Blue Extreme SAE 5W-40 Full Synthetic Diesel Engine Oil 1 GA, Case of 3
  • EXCELLENT WEAR PROTECTION IN HEAVY DUTY APPLICATIONS that can take a toll on critical internal moving parts
  • RESISTS OXIDATION AND FIGHTS DEPOSITS & SLUDGE with higher quality synthetic base oils and special inhibitors
  • PROTECTS DURING COLD START UPS WHILE CONTROLING SOOT as heavy-duty equipment can sit idle for extended periods of time
  • ADVANCED FUEL ECONOMY up to 1.5% over 15W-40 conventional oils in on-highway operations
  • UNIQUE 5,000 MILES OIL DRAINS EXTENSION in Cummins X15/X12 engines when average is 7mpg or higher

Buyer’s Guide

Before you run ahead and purchase oil for your Duramax engine, there are a few important considerations to bear in mind first.

We will discuss some vital factors that make up top-quality oil. Read on to discover what to look out for to make your decision process that little bit easier.


The viscosity grade is the rate of flow of oil at a definitive temperature. The oil will typically flow quicker into the engine at lower temperatures if it is a lower grade. It is crucial you understand the viscosity grade as it tells you the speed at which the oil will flow into the engine.

This reduces any friction in the engine and speeds up the starting time of your vehicle in cold weather. It’s important that oil continues with the same level of viscosity after a long time for the engine to sustain optimum power.

To ensure you find the right oil, check your car’s manual for the correct viscosity grades. If you are in low temperatures, thin oil is advised while thicker oil is best suited to hotter temperatures.


Oil manufacturers usually use their own blend of additives for their formula. These additives help with certain properties to help the engine power better.

Some work by cleaning the engine to help it run efficiently and ensure the oil doesn’t become too thin under hot temperatures.

Some different categories of additives are:

  • Detergent – This prevents rust built-up, soot, and other deposits from gathering on the engine’s surface
  • Dispersant – An additive that prevents solid particles from forming in the oil. This blocks any sludge formation within the engine
  • Corrosion inhibitors – This slows down the gathering of water or moisture, preventing rust
  • Viscosity improvers – Prevents thinning of the oil’s viscosity in high temperatures
  • Antiwear agents – This protects the vehicle’s metal surface from wear and tear
  • Friction modifiers – Prevents friction in the engine components which helps improve fuel economy

Fuel efficiency

Good quality engine oil will improve your car’s fuel economy as it will flow faster, keeping the engine’s heat at a safer, lower level.

If the motor is at the correct temperature, the whole car will run more efficiently and be ecologically safer. Always look for engine oil that states it will give a higher fuel economy percentage.


You need to make sure engine oil is compatible with your existing oil. If this is not the case, you must drain the current oil inside your engine so no problems occur when you use your new oil.

Not all engine oil is compatible with Duramax so check your car’s manual for the correct type. 

Your purpose of driving

The right oil for your Duramax engine will make your engine perform better. You need to choose oil depending on your vehicle’s workload.

If you typically carry or pull heavy loads, you should look for heavy-duty oil that will work well in all conditions.

Frequently Asked Questions

When is the best time to change the oil?

Simply check your owner’s manual to see how often the oil needs to be changed.

This usually needs to be done every 5,000 miles but it can be changed more frequently if you do a lot of heavy hauling or off-roading.

How long can you store oil?

Motor oil can last up to 5 years, depending on where it is stored. It needs to be properly stored, in a dry, mild, indoor space.

Temperature, water, and oxygen can negatively affect the quality of engine oil pretty quickly.

What happens if you forget to change your oil?

Forgetting to change your engine oil can seriously harm your car’s engine. It can become too hot and begin to malfunction.

Your engine will ultimately wear quickly before dying completely. It is crucial you change your oil regularly to save you money and hassle.