Diesel is expensive right now. You already know that if you’ve filled anything this month.
The number, for the record: EIA’s weekly on-highway average hit $6.285 a gallon for the week of September 14, 2026, up almost 32 cents from the week before. A year ago it was $3.74.
Some context before anybody panics. Adjusted for inflation, we’ve been higher. The 2008 peak works out to about $7.20 in today’s money, and the 2022 spike lands around $6.56. This is a real hit to your fuel line, but the industry ran through worse and kept running.
We’re writing this because customers have been calling to ask whether they should rethink their whole standby plan. For most of them the answer is no. There are four or five things worth adjusting, and one decision that has genuinely changed.
Why Is Diesel More Expensive Than Gasoline Right Now?
Diesel is setting records during weeks when crude oil isn’t particularly expensive. If oil were the whole story, those two would move together. They haven’t.
The squeeze is on distillate specifically, the category covering both diesel and home heating oil. EIA is forecasting US distillate inventories to drop below 100 million barrels this month and stay under the five-year low through the end of 2026 and most of 2027. Refining is the bottleneck. Domestic refinery capacity has come down over the past couple of years, export demand has been pulling barrels out of storage all year, and refining margins on diesel have run into record territory.
Timing isn’t helping. Fall is when refineries go down for maintenance, so production dips right as harvest demand picks up. Then heating season starts and the Northeast pulls on the same barrel your generators run on. EIA expects margins to ease through mid-2027, though that forecast leans on international shipping normalizing sooner rather than later. We’d plan as though it takes a while.
Where you sit matters too. Gulf Coast diesel is running about $6.03 while the West Coast is at $7.25, a spread of more than a dollar a gallon between regions. Our Texas and Florida customers are buying on the cheap end of a very expensive market. That’s still an expensive market.
How Much Does It Cost to Run a Diesel Generator per Hour in 2026?
Rule of thumb on a diesel genset is roughly 0.07 gallons per kWh. At $6.285 a gallon, that gives you:
| Generator size | Rough burn at full load | Fuel cost/hr (Sept 2025) | Fuel cost/hr (Sept 2026) |
|---|---|---|---|
| 100kW | 7 gal/hr | $26 | $44 |
| 500kW | 35 gal/hr | $131 | $220 |
| 1MW | 70 gal/hr | $262 | $440 |
| 2MW | 140 gal/hr | $524 | $880 |
Those are planning numbers, not spec sheet numbers. Real consumption depends on load factor, engine family, unit age, and what the weather’s doing. Most standby sets never see full load during an actual event anyway.
In practice, a two-day outage on a 1MW unit costs you around $21,000 in fuel now instead of the $12,500 it would have run last fall. If you built your annual fuel budget off last year’s average, you’re short by better than half.
None of this changes whether you need standby power. You’re not comparing fuel cost to zero. You’re comparing it against what an outage costs you, and for most commercial and industrial facilities that number runs to thousands of dollars per hour once you count lost production, spoiled product, and idle labor. Hospitals, data centers, and water treatment operations are in a different category again, where the cost isn’t measured in dollars at all. A few hundred dollars an hour in diesel doesn’t move that comparison.
Should You Still Load Bank Test at These Prices?
Yes, and we know how that sounds coming from the people who sell load bank testing.
The reasoning holds anyway. Fuel for a load bank test is a few hundred dollars. Finding out during a hurricane that a unit won’t hold its rated load is a different number entirely, and NFPA 110 requires annual load testing regardless of what fuel costs.
The service side of this matters more than usual right now. Expensive fuel makes three maintenance problems into money problems:
Stale or contaminated diesel is one of the most common reasons a unit won’t start when it’s needed. Water intrusion and microbial growth in tanks that sit for months are routine findings, and fuel polishing costs a fraction of what a failed start does.
Oversized units running at low load waste fuel continuously and wet stack on top of it. Plenty of facilities are carrying a 750kW set on a 200kW load because that’s what got specified a decade ago. At $6 diesel, that inefficiency shows up on an invoice.
Untuned engines burn more. Injectors, air filters, and governor settings all drift, and nobody notices until someone looks at gallons per hour against the baseline.
Our field techs are EGSA certified and handle all of this, along with the load bank testing itself. A fleet assessment is usually the cheapest way to find out which of the three you have.
Does Expensive Diesel Change the New vs Used Generator Decision?
Not directly. What’s changed is the delivery window underneath it.
Lead times are ugly. Large gensets, medium-voltage switchgear, transformers, UPS, and transfer switches are all running two to four times where they sat before 2020. A generator order that used to ship in 20 weeks is taking 60. Get into the big frame sizes and OEM backlogs run into 2028, mostly because data center construction has eaten the manufacturing capacity.
Specials go to the back of the line. You might get a 1MW unit reasonably quick, but ask for 48 or 72 hours of runtime, or a sound enclosure at a specific decibel rating, and you’re not waiting for unit 32 of 70 in the queue anymore. You’re waiting for unit 71. We’ve watched a water site in Centennial sit on temporary power with a finished building because the generator ordered almost two years ago still hasn’t shown up.
Tested used equipment out of dealer stock ships in one to four weeks.
So ask what a year of waiting actually costs you. Sometimes it’s deferred revenue. Sometimes it’s carrying construction financing on a building that can’t open, lease payments on a facility that isn’t producing, or a compliance deadline you’re going to pay to miss. Put a dollar figure on that and compare it against the price difference between a new unit and a documented used one. We’ve had projects this year where the delay cost more than the entire equipment savings. We’ve had others where it genuinely didn’t matter and new was the right call.
One thing we’ll push back on, including when it comes from our own industry. The efficiency argument for new equipment gets oversold on standby applications. Newer Tier 4 Final engines do burn less, but on a unit that runs forty or fifty hours a year the absolute savings are small. That argument carries real weight on prime power and continuous duty, where you’re logging thousands of hours annually and the fuel difference compounds. On standby it rarely justifies the price gap by itself. Run your own runtime numbers before you accept it from anybody, us included.
New equipment is still the answer in plenty of cases. Strict air district requirements rule out older units. Your lender or insurer wants a manufacturer warranty. Your project timeline honestly has sixty-plus weeks of room in it. Fine. The point is that the premium you’re paying for new right now includes a wait that’s longer than most people budget for.
If you do go used, get documentation. A recent load bank report at rated kW, verified hour meter records, and the ability to go look at the thing before money moves. An undocumented unit and a documented one at the same price are not the same purchase. One bright spot in the current market is that data center refresh cycles are pushing low-hour units into the secondary market, so the same demand that created the backlog has improved what’s available used.
What If You’re Already Stuck Waiting on an Order?
Rent. This is the option most people skip past, and it’s the right one more often than it gets used.
If your building is finished and your generator is twelve months out, bridge power keeps the project moving instead of holding a completed facility hostage to a queue position. Same logic applies if your existing unit failed and the replacement is on backorder, or if a temporary load increase means your current set is undersized for the next two quarters.
The fuel math on rentals is worth running carefully at these prices, because a rental unit running as prime power burns continuously rather than forty hours a year. Size it right. An oversized rental on a light load will cost you more in diesel than the rental rate does.
What We’d Do in the Next Couple Months
Reprice fuel for winter. Budget somewhere in the $6.25 to $6.75 range with a little room, not last year’s average.
If you keep bulk fuel on site, topping off before heating season competes for the same supply is reasonable. Pair it with testing and polishing.
Pull your load factor numbers. If you’re running well under 30 percent of nameplate, that’s worth a conversation.
Keep the testing schedule. We said it above and we’ll say it again.
And if capital equipment is anywhere on your 2027 plan, start now. The holdup isn’t going to be budget approval. It’s going to be availability, and those two sit on completely different clocks.
Common Questions
How much diesel does a 1MW generator use per hour? Roughly 70 gallons per hour at full load, using a planning figure of 0.07 gallons per kWh. At September 2026 prices that’s about $440 an hour. Actual burn depends on load factor and engine family, and most standby units never run at full load during an event.
Is diesel at $6 a gallon a record? It’s a nominal record. The $6.285 weekly average for September 14, 2026 is the highest figure in EIA’s series, which begins in 1994. Adjusted for inflation, both the 2008 and 2022 peaks were higher.
How long are industrial generator lead times right now? New OEM orders are running 60 weeks or more for large gensets, with backlogs into 2028 on big frame sizes. Custom configurations take longer. Tested used equipment from dealer inventory typically ships in one to four weeks.
Should I still exercise my generator monthly with fuel this expensive? Yes. Monthly exercise and annual load bank testing are required under NFPA 110, and the fuel cost is minor against the cost of a failed start. If fuel spend is the concern, the better lever is correcting an oversized unit running at low load.
Does Generator Source rent generators? Yes. We sell, service, rent, and buy commercial and industrial generators from 20kW to 4MW+, including bridge power for projects waiting on OEM deliveries.
Talk It Through With Us
Generator Source has been doing this for 45 years, and immediate availability has been the point since the beginning. We own our inventory outright rather than brokering someone else’s, which is why what’s on our yard is available in weeks instead of quarters. Every unit comes into one of our sites, goes through a 31-point inspection, and gets load bank tested before it’s certified and sold.
If you want help comparing a used unit at your spec against the delivery window on a new one, need bridge power while an order sits in a queue, or aren’t sure your current set is sized right for what fuel costs now, call us and we’ll walk through it.
Generator Source sells, services, rents, and buys commercial and industrial generators from 20kW to 4MW+, with branches in Jacksonville and Pensacola, Florida, Austin, Texas, and headquarters in Brighton, Colorado.
Sources
- US Energy Information Administration, Gasoline and Diesel Fuel Update, week of September 14, 2026
- US Energy Information Administration, Short-Term Energy Outlook, distillate inventory and refining margin forecasts
- Reuters, US diesel national average tops $6 a gallon, September 2026
- NFPA 110, Standard for Emergency and Standby Power Systems
- Generator Source internal equipment, service, and lead-time data