Diesel Hit a Record $6.53. Is a Used Diesel Truck Still Worth It?
Diesel now costs almost $2 a gallon more than gas, triple last year's gap. At that spread, most used half-ton diesels cost more to fuel than their gas siblings. Here's the math by truck, what's driving diesel prices, and what to check on a used diesel before you buy.
Mirko10 min read
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Diesel set an all-time record of $6.53 a gallon on September 22, according to AAA, beating the June 2022 high of $5.81. It has eased only slightly since: the EIA's weekly survey put it at $6.38 on September 28, against $3.75 a year earlier.
The number that matters most if you're shopping for a truck is the gap between diesel and gas. A year ago, diesel cost 64 cents a gallon more than regular. Now it costs $1.92 more. That gap decides whether a diesel's better mileage saves you money or costs you money, and right now it mostly costs.
The numbers at a glance
| Metric | Now | A year ago |
|---|---|---|
| Diesel, national average (EIA, Sept 28) | $6.38 | $3.75 |
| Regular gas, national average (EIA, Sept 28) | $4.47 | $3.12 |
| Diesel premium over gas | $1.92 a gallon | $0.64 a gallon |
| Diesel all-time high | $6.53 (Sept 22, 2026) | Old record: $5.81 (June 2022) |
| US distillate inventories (Sept 18) | 107.4 million barrels | |
| EIA forecast, 2026 average diesel | $5.07 | |
| EIA forecast, 2027 average diesel | $4.40 |
Sources: EIA Gasoline and Diesel Fuel Update, AAA, EIA weekly distillate stocks, EIA Short-Term Energy Outlook.
Why diesel is worse than gas
Gas prices follow crude oil. Diesel also depends on how many refineries can turn crude into diesel, and the world is short on them. Refinery outages in the Middle East and Russia have cut global supply, and with tensions involving Iran pushing crude above $100 a barrel several times this year, Chase notes that diesel has taken the harder hit. S&P Global reported in August that the US has few quick ways to boost its own refining output.
The EIA's September outlook says tightness in the global market "has raised domestic prices and incentivized U.S. exporters to increase distillate exports." It expects US distillate inventories to drop below 100 million barrels in September and to stay below the five-year low through much of 2027. The forecast has diesel averaging $4.40 next year, down from today, but still about $1.05 above gas, well above last year's gap.
In other words, even if oil prices fall, the diesel premium is likely to stay wide for at least another year.
The half-ton diesel math
Here's a year of fuel at 15,000 miles for the diesel and gas versions of the three best-selling full-size pickups, using EPA combined ratings from fueleconomy.gov for 4WD trucks:
| Truck (4WD) | EPA mpg | Sept 2025 prices | Today | 2027 forecast |
|---|---|---|---|---|
| 2021 Ford F-150 3.0L Power Stroke diesel | 23 | $2,448 | $4,162 | $2,870 |
| 2021 Ford F-150 2.7L EcoBoost | 21 | $2,227 | $3,189 | $2,393 |
| 2021 Ford F-150 3.5L PowerBoost hybrid | 24 | $1,949 | $2,791 | $2,094 |
| 2021 Ram 1500 3.0L EcoDiesel | 24 | $2,346 | $3,989 | $2,750 |
| 2021 Ram 1500 3.6L V6 eTorque | 21 | $2,227 | $3,189 | $2,393 |
| 2023 Chevrolet Silverado 3.0L Duramax | 24 | $2,346 | $3,989 | $2,750 |
| 2023 Chevrolet Silverado 2.7L turbo | 19 | $2,462 | $3,525 | $2,645 |
| 2023 Chevrolet Silverado 5.3L V8 | 17 | $2,751 | $3,940 | $2,956 |
Our calculations: 15,000 miles divided by EPA combined mpg, times the price per gallon. Diesel and gas prices from the EIA weekly survey (late September 2025 and September 28, 2026) and the EIA's 2027 forecast ($4.40 diesel, $3.35 gas).
A year ago, the diesel F-150 cost about $220 a year more to fuel than the 2.7L EcoBoost. Today it costs about $970 more, and the PowerBoost hybrid beats both by a wide margin. The Ram EcoDiesel now costs about $800 a year more than the V6. The only diesel on the list that still roughly breaks even is the Duramax Silverado, and only against the thirsty 5.3L V8.
Here's the rule of thumb. At today's prices, a diesel needs to get about 43% better mileage than the gas truck you're comparing it to just to cost the same to fuel. A year ago it needed about 20%. Against the popular gas V6 and turbo engines, half-ton diesels rate about 10% to 26% better on the EPA test, so today they lose. At the EIA's 2027 forecast, the bar is about 31%, still higher than most half-tons clear.
Where diesel still wins
The table above is unloaded driving. Diesels usually hold their mileage better than gas engines when towing heavy, so if you pull a big trailer often, the real-world gap narrows. Diesels also offer more range per tank and more low-end torque, which is why they dominate heavy-duty trucks.
Heavy-duty pickups like the F-250, Ram 2500 and Silverado 2500HD aren't required to carry EPA fuel economy ratings, so there's no official number to compare. If you tow near the limit of a half-ton, the choice is usually between a heavy-duty diesel and a heavy-duty gas V8, and that decision depends more on how often and how heavily you tow than on fuel price alone.
If you don't tow much, a used half-ton diesel is now a truck you'd buy for the torque and the range, not to save money.
What to check on a used diesel
Fuel is only part of the cost. Diesels carry emissions equipment and engine-specific risks that gas trucks don't, and a history report won't show most of them.
Emissions equipment and "deletes"
Every diesel pickup built in the last decade uses a diesel particulate filter (DPF), a selective catalytic reduction (SCR) system that runs on diesel exhaust fluid (DEF), and an exhaust gas recirculation (EGR) system. They're expensive to repair, and some owners illegally remove them.
Pickup Truck Talk, citing EPA enforcement data, puts the number of diesel pickups with emissions equipment removed at more than 500,000, about 13% of the certified diesel fleet. Vehicle history reports don't show deletes, because nothing requires anyone to report them. A deleted truck can fail inspection in states that check emissions, and putting the equipment back can cost $5,000 to $10,000, according to the same report.
Signs to look for: a straight exhaust pipe with no DPF canister, a missing or empty DEF tank, aftermarket tuning devices plugged into the diagnostic port, and a seller who describes the truck as "tuned" or "delete-ready." A diesel shop can scan the engine computer for tuning in a few minutes.
If the DEF system fails on a truck with its emissions equipment intact, the truck will warn you and eventually limit your speed until it's fixed. Check that no emissions or DEF warnings are showing, and ask for records of DPF service.
Engine-specific issues
- Ram 1500 EcoDiesel (2014-2019): A recall covering about 108,000 trucks (NHTSA 19V757) replaces the EGR cooler, which can crack and let coolant combust in the intake manifold, creating a fire risk. Confirm it was done.
- Chevrolet Silverado and GMC Sierra 3.0L Duramax (LM2, 2020-2022): The oil pump is driven by a belt at the back of the engine, due for replacement at 150,000 miles, and the transmission has to come out to reach it. Pickup Truck Talk puts the job at $1,000 to $3,000. The updated LZ0 engine (2023 and newer) stretches the interval to 200,000 miles. On a high-mileage LM2, ask whether it's been done or budget for it.
- Heavy-duty diesels with the Bosch CP4 fuel pump: Owners of 2011-2016 Silverado and Sierra HD trucks with the 6.6L LML Duramax sued over pump failures that can contaminate the whole fuel system, and GM agreed to a $50 million settlement in 2025. Ford's 6.7L Power Stroke trucks have faced similar lawsuits. On these trucks, service records for the fuel system matter.
Engines that are no longer sold new
Ford dropped the F-150's 3.0L Power Stroke after the 2021 model year, citing low demand, and Ram ended the 1500 EcoDiesel after 2023. Both trucks can still be serviced, but they were low-volume engines, so fewer independent shops know them well, and parts can take longer. The Silverado and Sierra are the only full-size half-tons still sold with a diesel.
Should you buy a used diesel truck now?
A used diesel can still make sense if:
- You tow heavy and often. That's where diesel earns its keep.
- You're comparing it to a thirsty gas V8, like the Duramax against the 5.3L.
- The price reflects today's fuel math. Diesel trucks have historically carried a premium, and that premium should be shrinking now.
- The emissions equipment is intact, the recalls are done, and there are service records.
A gas or hybrid truck is likely the better buy if:
- Your truck mostly carries you to work and back. The F-150 PowerBoost hybrid is cheaper to fuel than any diesel on our list at today's prices.
- You drive fewer than 15,000 miles a year, which leaves less fuel spending for a diesel to save on.
- The diesel you're looking at is high-mileage, near a major service like the LM2's oil pump belt, or has any sign of emissions tampering.
For more on what's driving fuel prices and what they're doing to used car prices overall, see our 2026 fuel crisis breakdown. If you're weighing the 2014-2019 generation of Silverado, our K2XX Silverado buyer's guide covers its known issues.
Final thoughts
Diesel's efficiency advantage hasn't changed. What changed is the price of the fuel. At a $1.92 gap, most half-ton diesels cost more to run than the gas versions of the same truck, and the EIA expects the gap to stay wider than usual into 2027. Buy a diesel for the work it does, and price the truck as if fuel will stay expensive.
Before you rush into a decision on a specific truck, a Squeezed report gives you the full risk picture in about a minute: the known issues for that year, engine and trim, open recalls, and what a fair price looks like. It's the step between the news headlines and your offer.
Sources
- U.S. Energy Information Administration, Gasoline and Diesel Fuel Update (September 28, 2026)
- U.S. Energy Information Administration, Short-Term Energy Outlook (September 9, 2026)
- U.S. Energy Information Administration, Weekly U.S. Ending Stocks of Distillate Fuel Oil
- AAA, Gas Prices (diesel record, September 22, 2026)
- Chase, Diesel Prices Keep Hitting Records in September 2026 (September 23, 2026)
- S&P Global, US Has Few Options to Boost Refining Amid Global Diesel Shortage (August 26, 2026)
- U.S. Department of Energy and EPA, fueleconomy.gov (EPA combined ratings)
- Pickup Truck Talk, Used Diesel Pickup Buyers Are Inheriting Emissions Delete Histories That Vehicle Reports Never Show (May 2026)
- Pickup Truck Talk, GM Duramax Lead Engineer Explains: Oil Pump Belt, Reliability (June 30, 2026)
- NHTSA, Recall 19V757: Ram 1500 3.0L EcoDiesel EGR cooler
- GM Authority, Faulty Diesel Fuel Pump Settlement Will Cost GM $50M (May 2025)
- Automotive Fleet, Ford Drops F-150 Diesel Option (July 2021)
- Autoblog, Ram 1500 EcoDiesel Discontinued (September 14, 2022)
FAQ
Is a used diesel truck worth it in 2026?
For towing heavy and often, it can be. For everyday driving, most half-ton diesels now cost more to fuel than their gas versions. With diesel $1.92 a gallon above gas, a 2021 F-150 Power Stroke costs about $970 a year more to fuel at 15,000 miles than the 2.7L EcoBoost.
Why is diesel so much more expensive than gas right now?
Diesel depends on refining capacity as well as crude oil, and global refining is short after outages in the Middle East and Russia. The EIA expects US distillate inventories to stay below the five-year low through much of 2027 and forecasts diesel averaging $4.40 next year, about $1.05 above gas.
How do I know if a used diesel truck has been deleted?
Look for a straight exhaust with no DPF canister, a missing or empty DEF tank and aftermarket tuners in the diagnostic port, and have a diesel shop scan the engine computer. Vehicle history reports do not show emissions deletes, and restoring the equipment can cost $5,000 to $10,000.
Which half-ton pickups still come with a diesel?
Only the Chevrolet Silverado 1500 and GMC Sierra 1500, with the 3.0L Duramax. Ford dropped the F-150's 3.0L Power Stroke after 2021, and Ram ended the 1500 EcoDiesel after 2023.
