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8 Crucial Perks and Pitfalls of GM’s Duramax Engines


Chevrolet pick up truck with Duramax Engine


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Until 1998, General Motors (GM) was seriously lacking in the diesel department. Their 1980s attempt at competing with Ford and Dodge with their 6.2 and 6.5 liter (L) engines, albeit mechanically impressive, only solidified their lower-tier placement in the world of power and torque.

But in 1998, GM collaborated with Isuzu to break ground on their 60:40 joint venture, DMAX Ltd. Two years later, the pair would release a diesel powerhouse, the Duramax engine. With more power, torque, and reliability, GM (or, more accurately, DMAX) is now lauded for its diesel engines.

Whether you have a GMC Sierra or a Chevrolet Silverado, you may be interested to know the advantages and disadvantages of the Duramax engine. To give you some insights, BenchForce, a leading provider of engine harnesses and engine programming hardware, laid out the eight perks and pitfalls you should be aware of.

Duramax Engines

  • LB7: 2001-2004
  • LLY: 2004-2006
  • LBZ: 2006-2007
  • LMM: 2007-2010
  • LML: 2011-2016
  • L5P: 2017-Present

GMC Truck with 3.0L Duramax driving on a field

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1. Perk: Long Lifespan

These diesel workhorses are known for their long lifespan. Whether you’re using your truck to haul heavy loads or tow a trailer, you can count on Duramax to get the job done for well over 100,000 miles without major repairs. In fact, GM covers 2500 and 3500 Series Heavy Duty (HD) Pickups equipped with a 6.6L Duramax Turbo-Diesel engine for 5 years or 100,000 miles.

Beyond their guarantee, many truck owners squeeze 300,000 miles out of their vehicles without major repairs. Anecdotally, there are reports of people getting nearly 500,000 miles out of their Duramax engines with regular maintenance.

2. Pitfall: Pricy

Without question, GM knocked it out of the park with the Duramax engine, but it comes with a hefty price tag. For instance, for a new Silverado, you’re looking at spending $38,000+ for the base model (if you can even find one in a reasonable timeframe). However, if you’re looking for more power and comfort, it’s not uncommon for packages to run north of $75,000, especially with the Silverado HD.

Used, you’re still looking at $30,000 for base models. If you’re swapping a Duramax in your own truck, the price typically varies between $8,500-$15,000 for a refurbished engine and around $25,000 for a new one.

3. Perk: Fuel Efficient

It may ease the pain of the price tag, knowing that Duramax is less expensive than a lot of its gasoline and diesel counterparts. For instance, according to, the 2023 Silverado—as well as an array of other Duramax-equipped vehicles—tops the charts for city and highway mileage.

Chevy with Duramax 6.6L Turbo-Diesel V8 engine hauling trailer

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4. Pitfall: Expensive Repairs

By and large, diesel engines can work longer and harder without the need for maintenance and repairs. But, when the time comes, the service costs can be expensive. Depending on the particular service, you could be looking at between two to six times as much for repairs than you would with a gasoline engine alternative.

5. Perk: Power

The Duramax V8 is an absolute workhorse. Depending on the year of your engine, you’re looking at between 250-550 hp and 460-1,050 lb-fit torque. So, whether you’re climbing steep hills, towing hefty trailers, or hauling heavy loads, you’re covered.

When it comes to power, many auto enthusiasts prefer Duramax over Cummins engines. This testament to Duramax says a lot considering trucks with Cummins engines are undeniable road warriors.

6. Pitfall: Some Years Have Problems

Duramax engines are incredible, but some years are better than others. Case in point, the 2011-2016 Duramax LML is known to have issues with its fuel pump, sensors, and exhaust fluid heater, which can set you back thousands of dollars. Moreover, the 2004-2005 LLY is notorious for poor fuel injectors and head gasket issues.

With regular repairs, Duramax allows a reliable choice. But, to reduce headaches and soften the blow on your wallet, do some research about the model you’re investing in.

7. Perk: Aftermarket Parts

If you’re looking to max out the potential of your Duramax engine, you’ll have the opportunity to tune it to your heart’s desire. At BenchForce, we’ve heard from customers who have been able to push another 100-200 hp out of their trucks.

8. Pitfall: High Demand

While there are whispers of the inventory shortage coming to an end, the supply is still limited at many dealerships. Mix the low supply with high demand, and it makes it difficult to find a reasonably priced truck that doesn’t have 50,000-75,000 miles on it.

Duramax + BenchForce

To compete with Ford and Dodge, GM stepped it up with their Duramax engine. With so many electronic parts, auto enthusiasts who enjoy tuning engines are excited about the power they can extract from their diesel workhorses. If you’re looking for programming harnesses that allow you to power up an engine control unit (ECU) on the bench, browse BenchForce’s unrivaled Duramax selection.