No official test ranks Cummins, Power Stroke and Duramax by lifespan, and all three makers have long backed their diesels with 5-year, 100,000-mile coverage. On design, the Cummins inline-six is the simplest, with fewer cylinders and one cylinder head. On the largest public study of high-mileage trucks, Ford and GM heavy-duty pickups came out ahead of Ram. In real life, the engine that lasts longest is the one that gets clean fuel, fresh oil and tested coolant.
This is one of the oldest arguments in the truck world. Every brand has loyal owners with a 400,000-mile story, and every brand has a model year its fans would rather forget.
This guide swaps the arguing for evidence. You will see how the three engines differ, what “lasts longest” really means, what the public record shows about each family’s problems, and the steps that add the most miles to any of them. The facts come from manufacturer figures, federal recall records, court settlements and a published longevity study. We have not tested these engines, and we do not own a fleet of them.
Cummins vs Power Stroke vs Duramax
Three engines, one honest comparison
Engine figures are 2025 model-year numbers. Recall and settlement details are from public records. Longevity percentages are from the iSeeCars study published in 2023.
Quick answer
There is no proven winner. The Cummins 6.7 is an inline-six with fewer moving parts and a strong reputation for long life. The Power Stroke 6.7 and the Duramax 6.6 are V8s that make their power more smoothly and have matured into dependable engines. In the iSeeCars study, the Ford F-350 was the vehicle most likely to reach 250,000 miles, with GM’s heavy-duty trucks close behind and Ram’s lower. But that study counts whole trucks, not engines alone. For any of the three, fuel quality and maintenance matter more than the badge.
How we put this guide together
We have not tested these engines. Power and torque figures are 2025 model-year numbers reported from the manufacturers. Recall information is from the National Highway Traffic Safety Administration. Settlement details are from court-approved class actions as publicly reported. Longevity percentages are from iSeeCars. Where we judge one design against another, we say that it is our view. No source we found publishes an official life expectancy for these pickup engines.
In this guide
- Meet the Three Engines
- What “Lasts Longest” Really Means
- How the Designs Differ, and Why It Matters
- What the Longevity Data Says
- Each Family Has Had a Rough Chapter
- The Warranty Tells You What the Makers Expect
- How to Make Any of Them Last
- Buying Used: How to Judge the Truck in Front of You
- Which One Should You Choose?
- Common Mistakes (and the Fix)
- Pro Tips for a Half-Million-Mile Attitude
- Real-Life Scenarios: Three Buyers, Three Answers
- Cummins vs Power Stroke vs Duramax: FAQ
- Your Diesel Longevity Checklist
Meet the Three Engines
Each of the Detroit truck makers sells one main diesel in its heavy-duty pickups.
| Point | Cummins 6.7 (Ram) | Power Stroke 6.7 (Ford) | Duramax 6.6 L5P (GM) |
|---|---|---|---|
| Layout | Inline six | V8 | V8 |
| Size | 6.7 liters | 6.7 liters | 6.6 liters |
| Horsepower | 430 | 475, or 500 in High Output form | 470 |
| Torque | 1,075 lb-ft | 1,050 lb-ft, or *1,200 in High Output form | 975 lb-ft |
| Cylinder heads | One, cast iron | Two, aluminum | Two, aluminum |
| Cold-start aid | Glow plugs from 2025. An intake heater before that | Glow plugs | Glow plugs |
| Built by | Cummins, for Ram | Ford | GM |
On paper they are close. All three make far more torque than most owners will ever use. The interesting differences are in how they are built, and that is where the longevity debate starts.
New to diesels? Our guide to gas vs diesel engines explains how they work.
What “Lasts Longest” Really Means
People ask this question as if an engine were one thing that wears out on one day. It is not. A modern diesel is three systems, and they age at different speeds.
| System | What is in it | How it usually ends | What protects it |
|---|---|---|---|
| The base engine | Block, crankshaft, pistons, bearings, heads | Slowly, by wear over a very long time | Clean oil and clean air |
| The fuel system | High-pressure pump, injectors, lines | Suddenly, when a part fails | Clean, dry fuel and fresh filters |
| The emissions system | EGR, DPF, SCR and DEF parts | In stages, with sensors and clogs | Complete regenerations and good DEF |
The base engines in all three trucks are strong. In the documented cases below, the trouble was in the fuel system or the parts around the engine, not in a worn-out block.
Engineers have a more exact way to talk about engine life. B10 life is the mileage at which 10% of engines are expected to need a major repair or overhaul. B50 life is the mileage at which half do. These figures are common for commercial truck engines. We could not find an official B10 or B50 figure published for any of these three pickup engines, so be careful with any number you see quoted online.
Key insight: “which engine lasts longest” is really three questions. Which base engine wears slowest, which fuel system fails least, and which emissions system gives the least trouble? The answers are not always the same brand.
How the Designs Differ, and Why It Matters
Here is where the Cummins stands apart. It is an inline-six. The other two are V8s.
| Point | Inline six (Cummins) | V8 (Power Stroke and Duramax) |
|---|---|---|
| Cylinders, pistons and injectors | 6 of each | 8 of each |
| Cylinder heads and head gaskets | 1 | 2 |
| Crankshaft main bearings | 7 | 5 |
| Engine length | Long | Short |
| Smoothness | Naturally balanced | Smooth, with a different sound |
| Room to work on it | Open sides | Tighter packaging |
The case for the inline-six. Fewer cylinders means fewer pistons, rings, valves and injectors to wear out or fail. One head means one head gasket. And the crankshaft is held by seven main bearings in place of five. Those are simple facts of the layout, and they are the main reason the Cummins has its reputation.
The case for the V8s. A V8 is shorter and fits the truck neatly. Eight smaller power strokes make for smooth, quick response. Ford and GM have also refined these engines over many years. The current Power Stroke dates from 2011 and the L5P Duramax from 2017, and both have been updated since.
Our view: the Cummins layout gives it an edge in the base engine. That is not the same as saying a Cummins-powered truck will outlast the others, because the fuel and emissions systems are a separate story, and so is the rest of the truck.
What the Longevity Data Says
There is one large public study that speaks to this. In 2023 the research firm iSeeCars analyzed more than 260 million vehicles sold between 2012 and 2022 to find the models most likely to reach 250,000 miles.
| Vehicle | Chance of reaching 250,000 miles |
|---|---|
| Ford F-350 Super Duty | 49.1% |
| GMC Sierra 2500HD | 41.3% |
| Chevrolet Silverado 2500HD | 41.2% |
| Ram 3500 | 24.3% |
| Average vehicle | 11.8% |
The Ford F-350 was first out of every vehicle in the study. GM’s heavy-duty trucks were close behind. The Ram 3500 scored lower, though still about twice the average.
Read this table with care
It would be easy to say “Power Stroke wins.” The data does not quite say that.
- It counts whole trucks. Transmissions, rust, electrics and how the truck is used all affect whether it reaches 250,000 miles.
- It includes gasoline engines. These model names are sold with gas and diesel engines, and the study does not separate them.
- It reflects owners as well as trucks. A truck bought by a fleet and one bought for weekend towing live very different lives.
So the fair reading is this. Heavy-duty pickups as a group last far longer than the average vehicle, and nothing in the data suggests a Ford or GM diesel is short-lived.
Each Family Has Had a Rough Chapter
Loyal owners often talk as if only the other brands have had problems. The public record says all three have. These are documented cases, not rumors.
| Engine and years | What happened | The record |
|---|---|---|
| Ford 6.0 Power Stroke, 2003 to 2007 | Owners reported failures of the EGR cooler, oil cooler, injectors and turbocharger | Ford settled a class action covering those repairs made before 135,000 miles or six years |
| GM Duramax LB7, 2001 to 2004 | Fuel injectors failed | GM issued special coverage for the injectors for 7 years or 200,000 miles |
| GM Duramax LML, 2011 to 2016 | Lawsuit over the Bosch CP4 high-pressure fuel pump | A settlement valued at $50 million won final court approval in May 2025 |
| Ram Cummins 6.7, 2019 to 2020 | The Bosch CP4 high-pressure fuel pump could fail and stall the engine | NHTSA recall 21V-880 covered 222,410 trucks |
Notice a pattern. Three of the four rows involve the fuel system, and two involve the same family of pump across two different brands. The base engines were not the problem.
That is the most useful lesson in this whole comparison. When you shop, ask about the exact model year and its fuel system, not just the name on the fender.
The Warranty Tells You What the Makers Expect
A warranty is the maker’s own bet on its engine.
| Maker | Diesel coverage | Worth knowing |
|---|---|---|
| Ford | 5 years or 100,000 miles on the diesel engine | Longer than Ford’s gasoline powertrain coverage |
| GM | 5 years or 100,000 miles on heavy-duty trucks with the 6.6 Duramax | GM’s standard powertrain coverage is 5 years or 60,000 miles |
| Ram | 5 years or 100,000 miles on diesel powertrains for many years | For 2026 Ram announced a 10-year, 100,000-mile limited powertrain warranty. Check the terms and dates |
For years the three were level. That tells you the makers saw no great difference in expected life at 100,000 miles. Ram’s newer offer is worth reading closely if you are buying new.
How to Make Any of Them Last
This is the part you control. It matters more than the badge.
- Follow the oil schedule for your real use. Towing, short trips and long idling all count as severe service. Use the exact oil specification in your owner’s manual, because each maker has its own.
- Change fuel filters on time, and drain the water separator. High-pressure fuel systems tolerate almost no dirt or water. This is the cheapest insurance on the truck.
- Buy fuel from busy stations. Fresh, clean fuel protects the pump and the injectors.
- Test the coolant. Additives wear out before the coolant looks bad.
- Replace the air filter by the restriction gauge. Dust that gets past the filter wears cylinders quickly.
- Let regenerations finish. Shutting off in the middle of a DPF cleaning cycle again and again leads to a clogged filter.
- Use fresh, sealed DEF and never let the tank run dry.
- Warm up gently and cool down briefly. Drive easily until the engine is warm, and let it idle a short while after hard towing before you switch off.
- Avoid needless idling. Hours of idling add wear and soot without adding miles.
- Keep every record. Dates, miles and what was done.
The intervals are in our diesel engine maintenance schedule, and the free Maintenance Interval Generator builds a checklist for your truck.
Four products that support a long engine life
Each had an active Amazon listing with an Add to Cart button when we checked in October 2026.
Know what is happening inside
Oil Analysis Kit for Gasoline and Diesel Engines (Prepaid Lab Test)
A kit for posting a small oil sample to a laboratory. The report shows wear metals, contamination and the condition of the oil.
- TypePrepaid laboratory test
- In the kitSample bottle, information card, sealable bag
- ReturnPrepaid mailer included
- EnginesGasoline and diesel
- Also forTransmission and differential oil
- Reports onWear metals, contamination, oil condition
- Why it works: it finds coolant, fuel or dirt in the oil long before the engine shows a symptom.
- Who it is best for: owners who tow hard, buyers of used diesels and anyone planning to keep a truck for a very long time.
- What it solves: guessing about oil change intervals and hidden wear.
- Handy to know: results mean more as a trend. Send a sample at every oil change and compare.
- Keep in mind: one sample is a snapshot. The listing notes it is not for aircraft engines.
As an Amazon Associate we earn from qualifying purchases. Specs come from the Amazon listing, checked October 2026.
A one-minute coolant check
Fleetguard CC2602 3-Way Coolant Test Strips (50 per bottle)
Dip-and-read strips for checking coolant condition at home or in the shop.
- TestsFreeze point, molybdate and nitrite
- Strips per bottle50
- Result time45 to 75 seconds
- Checks forLiner pitting protection
- Also checksCorrosion protection and dilution
- BrandFleetguard
- Why it works: one strip shows both the freeze point and the additive level.
- Who it is best for: owners of diesels whose coolant uses nitrite or molybdate additives.
- What it solves: worn-out coolant that still looks clean.
- Handy to know: fifty strips will last a single truck for years.
- Keep in mind: strips must match your coolant type. Many newer pickups use long-life coolants with different chemistry, so check what your manual specifies first. Only 13 bottles were in stock when we checked.
As an Amazon Associate we earn from qualifying purchases. Specs come from the Amazon listing, checked October 2026.
Protects the fuel system
Mopar Fuel Filter Set for Ram 6.7L Cummins (68157291AA and 68436631AA)
The factory primary and secondary fuel filters for 2020 to 2024 Ram trucks with the 6.7-liter Cummins.
- Fits2020 to 2024 Ram with 6.7L Cummins
- In the setPrimary and secondary filters
- Part numbers68157291AA and 68436631AA
- TypeGenuine Mopar
- RemovesDirt and water
- FittingDrops into the factory housings
- Why it works: two-stage filtering takes out both water and fine dirt before the fuel reaches the high-pressure pump.
- Who it is best for: Ram Cummins owners who do their own service.
- What it solves: the kind of contamination that damages pumps and injectors.
- Handy to know: changing both filters together keeps the whole system clean.
- Keep in mind: it fits only the model years listed. Check your truck’s year and part numbers before you order.
As an Amazon Associate we earn from qualifying purchases. Specs come from the Amazon listing, checked October 2026.
Oil made for diesel trucks
Mobil 1 Turbo Diesel Truck Full Synthetic Motor Oil 5W-40, 1 Gallon
A full synthetic diesel engine oil in a 5W-40 grade, sold for modern diesel trucks including low-emission engines.
- Grade5W-40
- TypeFull synthetic
- Size1 gallon
- Made forModern diesel truck engines
- SuitsLow-emission engines, as listed
- Stock when checkedIn stock
- Why it works: synthetic oil flows sooner on a cold start and resists heat under load.
- Who it is best for: owners whose manual allows a 5W-40 synthetic, most of all in cold climates.
- What it solves: thick oil on winter mornings and deposits from hard towing.
- Handy to know: the listing says it meets or exceeds the specifications of major truck manufacturers.
- Keep in mind: always match the oil to the exact specification in your owner’s manual. A grade that is right for one of these engines is not automatically approved for another.
As an Amazon Associate we earn from qualifying purchases. Specs come from the Amazon listing, checked October 2026.
Duramax owners can find the factory part as the GM Genuine Parts TP1015 fuel filter kit. Check it against your model year before you order.
Buying Used: How to Judge the Truck in Front of You
A well-kept truck from any of the three is a better buy than a neglected one from your favorite brand.
| Check | How | Why it matters |
|---|---|---|
| Open recalls | Enter the VIN on the NHTSA recall website | Recall repairs are free at a dealer |
| Service records | Ask for receipts with dates and miles | Proof of oil and filter changes |
| Engine hours | Read the hour meter in the dash menu | High hours with low miles means a lot of idling |
| Fault codes | Scan the truck | Stored codes show problems the seller may not mention |
| Oil condition | Send a sample to a laboratory | Shows coolant, fuel or heavy wear |
| Emissions equipment | Look underneath and check for warning lights | Missing or altered parts are illegal and costly to put right |
| Cold start | Start it from cold yourself | Hard starting and smoke show up then |
If the truck starts with white or black smoke that does not clear, read diesel smoke colors before you make an offer.
Which One Should You Choose?
Since none is proven to outlast the others, choose by how you will use it.
| If you value | Lean toward | Why |
|---|---|---|
| The simplest engine design | Cummins 6.7 | Six cylinders, one head, seven main bearings |
| The most power and torque | Power Stroke 6.7 High Output | 500 hp and 1,200 lb-ft |
| A smooth, quiet V8 with a 10-speed Allison-branded transmission | Duramax 6.6 L5P | Refined since 2017 |
| The strongest result in the iSeeCars study | Ford Super Duty | The F-350 topped the whole study |
| The longest new-truck powertrain warranty | Ram, if its newer warranty offer applies | Check the terms for your model year |
Then buy the truck that suits you in every other way: the cab, the ride, the dealer nearby and the price. A truck you like is a truck you will look after.
Common Mistakes (and the Fix)
Pro Tips for a Half-Million-Mile Attitude
- Think in hours as well as miles. A truck that idles a lot needs service sooner than the odometer suggests.
- Start oil analysis early. A baseline from a healthy engine makes later changes easy to spot.
- Keep a spare set of fuel filters in the garage.
- Fill up before the tank is low. It leaves less room for condensation.
- Fix small leaks at once. A coolant or boost leak makes the engine work harder.
- Read the cold-weather pages of your manual before winter. Our cold-weather diesel starting guide covers the basics.
- Record everything. A full service file adds real value when you sell.
If you run more than one truck, our diesel fleet schedule by miles and calendar shows how to plan the work.
Real-Life Scenarios: Three Buyers, Three Answers
These are typical situations that buyers describe in forums and reviews. They are examples to help you choose, not quotes from real people.
🚜 The keep-it-forever owner
You want one truck for 15 years of farm and trailer work, and you do your own service.
You need a simple engine with good access and a clean fuel history.
Best fit: the inline-six Cummins, in a model year without the recalled pump
🏁 The heavy tower
You pull a large fifth-wheel through the mountains several times a year.
You need the most torque and a strong warranty.
Best fit: the Power Stroke 6.7, kept strictly on schedule
🧾 The used-truck buyer
Your budget buys a ten-year-old truck with 150,000 miles.
You need proof of care more than a badge.
Best fit: whichever truck has the best records, a clean scan and no open recalls
Cummins vs Power Stroke vs Duramax: FAQ
Which diesel engine lasts the longest: Cummins, Power Stroke or Duramax?
There is no official ranking. The Cummins inline-six has the simplest design, with six cylinders and one cylinder head. In the iSeeCars study, Ford and GM heavy-duty trucks were more likely than Ram to reach 250,000 miles, but that study counts whole trucks, including gasoline models.
Is an inline-six diesel more reliable than a V8 diesel?
An inline-six has fewer cylinders, one head gasket and seven main bearings, so there is less to wear or fail in the base engine. That is a design advantage, not a guarantee. Fuel and emissions systems cause most modern diesel repairs on both layouts.
What is the warranty on a diesel pickup engine?
Ford and GM cover their heavy-duty diesel engines for 5 years or 100,000 miles. Ram offered the same for many years and announced a 10-year, 100,000-mile limited powertrain warranty for 2026. Confirm the terms for your model year.
What was the CP4 fuel pump problem?
The Bosch CP4 high-pressure fuel pump was used by more than one truck maker. Ram recalled 222,410 trucks from 2019 and 2020 because the pump could fail and stall the engine, and GM settled a lawsuit over the pump in its 2011 to 2016 Duramax trucks.
What is B10 or B50 engine life?
B10 life is the mileage by which 10% of engines are expected to need a major repair or overhaul. B50 is the mileage by which half do. We could not find official figures for these three pickup engines.
How can I make my diesel truck last longer?
Change the oil and fuel filters on time for your real use, buy clean fuel, test the coolant, let regenerations finish, avoid long idling and keep full records.
Your Diesel Longevity Checklist
- Choose by model year, not by brand name alone.
- Check for open recalls with the VIN.
- Ask for service records with dates and miles.
- Use the exact oil specification in the owner’s manual.
- Change oil for your real duty, not the best-case interval.
- Replace fuel filters on schedule and drain the water separator.
- Buy fuel from busy stations.
- Test the coolant at every service.
- Replace the air filter by the restriction gauge.
- Let DPF regenerations finish, and use fresh DEF.
- Keep idling to a minimum.
- Send an oil sample to a laboratory once a year.
The bottom line
Cummins, Power Stroke and Duramax are all capable of very high mileage. The Cummins has the simplest layout, Ford’s trucks top the best public longevity study, and GM’s sit right beside them. The real difference is the model year you pick and the care you give it. Buy the truck that fits your work, then protect its fuel, oil and coolant.
As an Amazon Associate we earn from qualifying purchases.
Sources: Manufacturer power and torque figures for the 2025 Ram, Ford Super Duty and GM heavy-duty pickups; National Highway Traffic Safety Administration recall 21V-880; court-approved settlements involving the Ford 6.0L Power Stroke and the GM Duramax LML fuel pump, as publicly reported; GM Special Policy 04039 on LB7 injectors; Chevrolet warranty documents; iSeeCars longest-lasting vehicles study, 2023; current Amazon listings for the products named in this guide. All checked October 2026.
