How to Get Better Fuel Mileage in a 6.6 Duramax – Best Tips

GMC Sierra or Chevy Silverado equipped with the 6.6L Duramax diesel engine, you may wonder how to get better fuel mileage in a 6.6 Duramax. The Duramax is known for its power and towing capability but is also notorious for its thirst for fuel.

The fuel Mileage depends on proper maintenance, which makes the vehicle engine fresh and longevity. In this article, we will explore some tips and tricks on how to get better fuel mileage in a 6.6 Duramax so that you can save money at the pump while still enjoying all the benefits of this impressive engine.

What is the Fuel Mileage for a 6.6 Duramax Diesel?

How to Get Better Fuel Mileage in a 6.6 Duramax

The fuel mileage for a 6.6 Duramax Diesel is a technique which many truck enthusiasts want to know. According to the EPA, the 2021 Chevy Silverado with a Duramax engine can achieve up to 23 miles per gallon on the highway and 18 miles per gallon in city driving conditions. These numbers are impressive for the engine’s size, power and Duramax longevity.

How to Get Better Fuel Mileage in a 6.6 Duramax?

You can take several steps to improve your truck’s fuel economy without sacrificing performance. From simple maintenance tasks to more advanced modifications, these tips will help you get the most out of your 6.6 Duramax and save money at the pump. 

How to Get Better Fuel Mileage in a 6.6 Duramax

Tire Pressure:

Tire Pressure:

Maintaining proper tire pressure is crucial for achieving optimal fuel mileage in a 6.6 Duramax engine. According to the Department of Energy, even a slight drop in tire pressure by 0.1 psi can decrease fuel efficiency by 0.4%. This may seem small, but it can add up over time and cost you money at the pump.

To get better fuel mileage in a 6.6 Duramax, it is vital to regularly check your tire pressure and inflate them to the recommended level specified by the manufacturer. Properly inflated tires improve gas mileage and enhance handling and braking performance while reducing the risk of blowouts and accidents on the road.

Drive in Economic/2WD Mode:

Driving in economic 2WD mode can help you get better fuel mileage in your 6.6 Duramax. This is because the 4WD mode requires more energy to power all four wheels, so the engine has to work harder and use more fuel.

When you switch to 2WD mode, some components, like the front driveshaft and front side shafts, are disengaged, reducing the energy needed to power your vehicle. Not only does driving in 2WD mode save fuel, but it also reduces wear and tear on your vehicle’s drivetrain components.

Use Premium Grade Diesel:

Premium grade diesel contains a higher cetane rating, allowing for better combustion and increased power output from your engine. With premium-grade diesel, you can experience better fuel mileage, which translates into savings on gas expenses.

A higher cetane rating means the fuel will ignite more easily and quickly in the engine, resulting in more efficient combustion and smoother operation. This means your engine will produce less smoke, providing better performance and longevity.

A premium diesel will provide you 5 benefits, including-

  • Quicker start-ups
  • Keep your engine clean
  • Reduce friction
  • Keep unwanted moisture out
  • Prevent deposits

Change Engine Oil Regularly:

How to Get Better Fuel Mileage in a 6.6 Duramax?

One of the most important things you can do to keep the Duramax engine running efficiently is to change the oil regularly. The general recommendation for an oil change interval in this type of engine is every 7,500 miles, but if you want to maximize your fuel mileage and extend the life of your vehicle, it’s best to change the oil every 6,000 miles instead.

But why does changing your oil more frequently affect fuel mileage? One reason is that clean oil helps to reduce friction between moving parts in the engine. When there’s less friction, the engine doesn’t have to work as hard to function properly – which means better fuel efficiency.

Synthetic engine oil will provide 07 benefits,

  • Maintaining a clean engine
  • Create a seal
  • Avoid rusting
  • Keep engine parts in top condition.
  • Reduce shock.
  • Exchange energy
  • Reduce wear and friction on the majority of engine parts.

Change Air Filter:

Change Air Filter:

Air filters are essential to keep harmful contaminants like dust, dirt, and debris out of your engine’s combustion chamber. When these particles accumulate within the filter over time, they restrict airflow into the engine.

As a result, it becomes harder for the engine to burn fuel efficiently, leading to reduced gas mileage and decreased power output by changing your air filter every 15,000 miles or according to manufacturer recommendations.

Changing the air filter in your Duramax 6.6 has many advantages.

  • For improved engine efficiency
  • To enhance fuel efficiency
  • It will keep black smoke away.
  • Improve the level of indoor air quality
  • Extend the lifespan of your HVAC system 
  • It will lower repair costs.

Add DEF Fluid Before it becomes Less than 5%:

DEF (Diesel Exhaust Fluid) is essential in modern diesel engines, including the 6.6 Duramax. DEF reduces around 90 per cent of pollution emitted by diesel vehicles, making it an eco-friendly solution for those who want to reduce their carbon footprint while driving their beloved trucks.

Adding DEF fluid into your tank before it drops below 5%‘ll ensure your engine operates smoothly and efficiently each time you hit the road.

You receive the following 6 advantages from DEF.

  • Maximize fuel efficiency
  • Reduction in maintenance
  • Better combustion
  • Safe emissions
  • Reduced regenerations
  • Improved reliability

Change the Glow Plug Every 100,000 Miles:

Glow plugs are crucial components of diesel engines as they provide heat to ignite the compressed fuel in the cylinders. They heat up when we turn on our engine, ensuring efficient combustion and proper ignition timing.

Changing your glow plugs every 100,000 miles ensures that your engine starts smoothly and efficiently and can also improve fuel mileage. A well-maintained engine with properly functioning glow plugs burns fuel more efficiently than one with worn-out or faulty plugs.

Change All Brake Pads Every 30,000 Miles:

The brake pads on your vehicle are a critical safety component that needs to be maintained regularly. Worn-out brake pads can reduce stopping power and increase the risk of accidents. Changing all brake pads every 30,000 miles is recommended to ensure proper functioning and avoid potential accidents.

Replace the brake pads right away if you see any of the following 6 symptoms:

  • The noise of squealing or squeaking
  • sound of grinding
  • vibrating when braking
  • The brake pad is warning light illuminates.
  • Spongy brakes
  • Larger stopping distance.

Don’t Neglect Warning Signs:

As a 6.6 Duramax owner, you might be familiar with the various dashboard warning signs that light up when something isn’t quite right with your vehicle. While green signs indicate safety, red and orange warning signs cannot be ignored as they signal potential problems that require immediate attention.

Neglecting these warning signs can negatively impact your truck’s performance and decrease fuel efficiency. One of the easiest ways to get better fuel mileage in a 6.6 Duramax is by paying attention to these warning signs and addressing any issues promptly.

Among them, 05 signs indicate serious problems which should not be avoided.

  • Examine the engine warning light.
  • Warning sign for oil pressure
  • Tire pressure warning indication
  • Electrical failure warning sign
  • The light indicates the coolant temperature

Don’t Idle Unnecessarily:

One way to achieve this goal is by reducing the amount of time you idle unnecessarily in your 6.6 Duramax engine. Idling your engine consumes fuel without providing any benefit, which can significantly decrease your overall fuel mileage.

It is estimated that idling for just 10 minutes daily can waste up to one gallon of diesel per week! Therefore, if you want to get better mileage out of your 6.6 Duramax engine, it is essential to reduce unnecessary idling as much as possible.

Lower Air Conditioner Use:

If you’re looking to improve the fuel economy of your 6.6 Duramax engine, adjusting your air conditioner usage is a simple and effective way to achieve it. The air conditioning system of a vehicle draws power from the engine, which can result in decreased fuel efficiency. So, by reducing the time you spend using your AC, you can increase your truck’s miles per gallon (MPG).

Basic Check Up in Every 15,000 Miles:

To increase the fuel mileage properly, you should check Duramax with mechanic or company workshops. There are different steps of check:

  • Basic checking/service:  15,000 miles
  • Thorough service:          30,000 miles and
  • Full service:                    12 months or once per year.

Different services are included in the primary check;

  • Checking engine oil and filters;
  • Engine other fluid levels;
  • Checking tire pressure;
  • Inspect your brakes;
  • Check the electrical system;
  • Check your gearbox and clutch.

Final Thoughts:

Optimizing fuel mileage in a 6.6 Duramax is not rocket science. Simple modifications can make a huge difference in improving gas consumption. Regular maintenance, proper tire inflation, and limiting the use of air conditioning are some of the easiest ways to increase fuel efficiency.

In this guide, we see How to Get Better Fuel Mileage in a 6.6 Duramax; these tips will go a long way in helping you save on gas expenses and protect the environment by reducing carbon emissions. Take action today and apply these techniques to enjoy better fuel mileage on your Duramax!


Can cold air intake increase fuel mileage?

The answer is yes but with some caveats. A properly designed and installed Cold Air Intake (CAI) system in Duramax can increase fuel mileage by improving combustion efficiency and reducing engine strain. By allowing cooler, dense air into the engine, a CAI system can help your car burn fuel more efficiently, resulting in better gas mileage.

Can using cruise control help improve fuel mileage?

Using cruise control on highways can help maintain a consistent speed and reduce unnecessary acceleration variations, thus improving fuel mileage in your 6.6 Duramax.

Can aftermarket modifications help enhance fuel mileage in a 6.6 Duramax?

While some aftermarket modifications claim to boost fuel mileage, it’s important to research and choose reputable brands that have been proven effective without compromising the vehicle’s warranty or emissions compliance regulations.

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