Quick Facts:
- Topic: Silverado E85 support ends on the 2027 Chevrolet Silverado 1500 and GMC Sierra 1500.
- Manual wording: “Do not use any fuel labeled E85 or FlexFuel.”
- Ethanol cap: 15 percent by volume on every gasoline engine.
- Gasoline engines: 2.7L TurboMax, 5.7L V8 and 6.6L V8, with none approved for E85.
- Diesel: the 3.0L Duramax runs on diesel, so E85 never applied.
- 2026 flex fuel: select 5.3L Work Truck and Pro trims, fleet and government orders only.
- Octane: 87 or higher for the 2.7L and 5.7L; 91 or higher recommended for the 6.6L.
- Showrooms: late 2026, per GM.
 6 min read
In This Article
Overview
Silverado E85 support ends with the 2027 model year on the light-duty 1500 pickups. According to GM’s owner’s manuals, the redesigned 2027 Chevrolet Silverado 1500 does not run on E85 flex fuel. Also, the 2027 GMC Sierra 1500 does not. Automotive outlets reported the change this week after reading the new manual wording.
Specifically, none of the three gasoline engines accepts E85. Those engines are the enhanced 2.7L TurboMax, the new 5.7L V8 and the new 6.6L V8. The 3.0L Duramax runs on diesel, so E85 never applied to it.
This change matters less than the headline suggests, however. For 2026, GM offered flex fuel only on select Work Truck and Pro configurations with the 5.3L V8. Because the option was limited to fleet and government orders, most retail buyers never had it.
No press release from Chevrolet or GMC turned up on the change. Instead, the evidence is the manual wording, which the next section quotes. This guide lays out the right fuel for each engine and what the change means for your next fill-up.
Because the manual caps ethanol at 15 percent, two universal products are worth a look. The REV X E85 Super Tester checks the ethanol content of a gasoline sample. Then the STP Complete Fuel System Cleaner covers routine upkeep. Its listing names direct injection engines as compatible. Neither product is tied to a specific truck.
Fuel-checking gear
What the Manual Says About Silverado E85
The 2026 manual wording, as reported this week, allowed E85 or FlexFuel only when a yellow sticker sat on the fuel door. Without the sticker, it limited ethanol to 15 percent by volume.
The 2027 manual drops the exception. It now reads: “Do not use any fuel labeled E85 or FlexFuel. Do not use gasoline with ethanol levels greater than 15 percent by volume.”
Still, the 15 percent cap is easy to apply at the pump. E10 and E15 gasoline both fall inside the limit, while E85 does not. The Department of Energy describes E85 as a blend with 51 to 83 percent ethanol. As a result, anything labeled E85 or flex fuel stays out of the tank.
Fuel Guide by Engine
Use this table before your first fill-up. Output figures come from the Chevrolet newsroom, and the fuel grades come from the 2027 manual wording.
| Engine | Output | Fuel in the manual | E85 |
|---|---|---|---|
| 2.7L TurboMax | 350 hp, 455 lb-ft | Regular, 87 octane or higher. | No. |
| 5.7L V8 | 402 hp, 428 lb-ft | Regular, 87 octane or higher. | No. |
| 6.6L V8 | 481 hp, 501 lb-ft | Premium, 91 octane or higher recommended; 87 is allowed when premium is unavailable. | No. |
| 3.0L Duramax | 305 hp, 495 lb-ft | Ultra-low-sulfur diesel. | Not applicable. |
First, the 2.7L and the 5.7L both take regular gasoline. The largest V8 is the exception. GM recommends 91 octane or higher, yet it allows 87 when premium is unavailable, with reduced performance and driveability.
Notably, GM gave the same advice for the 6.2L V8 the 6.6L replaces. Check which engine your trim gets in our 2027 Silverado engine chart. GM’s order guide also tags the 2.7L as TurboMax late availability on six trims.
Who Loses Silverado E85 Support and What E85 Offered
First, fleet and government buyers lose the most. In 2026, GM limited the option to select Work Truck and Pro configurations with the 5.3L V8. Notably, the option went only to those two buyer groups.
The new 5.7L V8 replaces the 5.3L V8, and it does not support E85. As a result, the one engine with a flex-fuel option is gone, and no replacement carries it. The Sierra shares the engines, so it follows the same rule; our 2027 GMC Sierra options guide lists its trims.
Station access is the other side of the story. The Department of Energy counts more than 4,200 public E85 stations in 43 states. Its ethanol benefits page also attributes reduced flex-fuel vehicle availability to recent changes to fuel economy credits. GM’s reasoning for the 2027 change remains unconfirmed.
E85 costs you range too. At an 83 percent blend, the Department of Energy says E85 holds about 27 percent less energy per gallon than gasoline. Therefore, a gallon of E85 needs to cost roughly 27 percent less to match gasoline on cost per mile. Owners of a 2026 flex-fuel truck should run this math against the price on the pump sign.
What This Means for You
If you own a 2026 flex-fuel truck, check the fuel door first. The 2026 manual still ties E85 use to the yellow sticker. As a result, no sticker means no E85, whatever the 2027 manual says.
Next, if you are buying a 2027, plan on pump gasoline up to E15. Match the octane to your engine. Our 2027 Silverado trim prices show what each trim costs, and the engine chart shows which engine sits under it.
If E85 matters to your fleet, ask a dealer whether any 2026 flex-fuel trucks remain. I did not confirm inventory or find GM guidance on a replacement.
Aftermarket sellers list flex-fuel conversion kits for older Silverados. For a 2027, I would not try one. The manual is explicit. Because I found no GM guidance on kits, ask a dealer how a conversion affects warranty coverage.
Whichever grade you pick, your own mileage shows how it performs. First, the Veepeak OBDCheck BLE Bluetooth OBD II Scanner pairs with phone apps such as Car Scanner and OBD Fusion for live engine data. Also, the AstroAI Digital Tire Pressure Gauge reads pressure within 1 psi, since tire pressure affects mileage. Record both over a few tanks, then compare regular with premium if you own the 6.6L.
Gear for tracking your own mileage
Veepeak OBDCheck BLE Bluetooth OBD II Scanner for iOS & Android
Final Thoughts
Overall, the headline sounds bigger than the change. Most Silverado 1500 and Sierra 1500 shoppers never had E85 on the order sheet. As a result, 2027 trucks need only regular or premium gasoline with ethanol at 15 percent or less.
I like how plain the new rule is. Do not use E85, keep ethanol at or under 15 percent, and match the octane to the engine. All three are easy to recall at the pump without opening the manual.
If E85 is required for your work, I would look at leftover 2026 flex-fuel trucks before ordering a 2027. Then I would confirm the sticker on the fuel door in person. Everyone else gets a simpler fuel decision. However, the buyer of the largest V8 gets the only real choice: pay for premium or accept reduced performance. Whichever way you go, you now know exactly what goes in the tank.
Frequently Asked Questions
Does the Sierra 1500 follow the same Silverado E85 rule?
Yes. The 2027 GMC Sierra 1500 shares its engines with the Silverado, and its manual carries the same E85 restriction. No gasoline Sierra engine accepts E85 for the new model year.
Is any 2027 Silverado engine approved for E85?
No. The 2.7L TurboMax, the 5.7L V8 and the 6.6L V8 are all off limits for E85. Because the 3.0L Duramax runs on diesel, E85 never applied to it.
Is a 2026 truck still compatible with Silverado E85?
Yes, but only if the fuel door carries the yellow sticker. The 2026 manual allows E85 or FlexFuel on stickered trucks, and it caps ethanol at 15 percent on the rest.
Will E15 pump gasoline work in a 2027 Silverado?
GM’s manual allows gasoline up to 15 percent ethanol by volume, so E15 falls within the limit. E10 sits well inside it. Anything above 15 percent, including E85, is off limits.
Is there a Silverado E85 conversion kit for 2027 trucks?
Aftermarket sellers list kits for older Silverados. I found no GM guidance on kits for the 2027, and the manual says not to use E85. Ask a dealer about warranty coverage first.