If you own a boat, a classic car or a garage full of small engines, the ethanol question matters more than the price. People search "is Costco gas ethanol free" because the pump label is easy to miss and Costco's own fuel pages say very little. This post sets out what is actually in Costco gas in the US and Canada, where Costco sells higher blends like E15, and where to go when you need fuel with no ethanol at all.
Short answer: Yes, Costco gas has ethanol. In the US it is normally E10, up to 10% ethanol, and Costco has said its Kirkland Signature gasoline contains ethanol to comply with the federal Renewable Fuel Standard. Costco does not market an ethanol-free grade or E85 anywhere we could find, and a few Midwest Costcos now sell E15 (Unleaded 88). Canadian gas bars also sell ethanol blends because of federal and provincial mandates, though whether premium contains ethanol varies by area and is not published by Costco.
Does Costco gas have ethanol?
Yes. Costco's US gasoline Q&A page said so directly: "The federal Energy Policy Act of 2005 established the Renewable Fuels Standard, which required that a certain amount of ethanol be used in the nations' fuel supply... Kirkland Signature Gasoline complies with this law, and an ethanol content label can be found on the pump." That page was live through at least February 2025. Its old address returned "page not found" when we checked on September 30, 2026, and Costco's current gas Q&A (costco.com/f/-/gasoline-qanda) no longer includes the ethanol statement. We found no newer Costco statement that changes the answer.
The same page explained that Costco uses "ethanol-compatible filters designed to catch sediment, water, or phase-separated ethanol and water mixtures." In other words, Costco designs its stations around ethanol blends. This is not a Costco quirk. The US Energy Information Administration says most gasoline sold in the US is E10, and Costco buys its base gasoline from the same terminals as other stations, which our post on where Costco gets its gas explains.
How much ethanol is in Costco gas?
Usually up to 10%, the blend called E10. The pump label typically reads "may contain up to 10% ethanol" or similar. "Up to" matters: the label sets a ceiling, not a guarantee, so a given tank can hold less.
The exception is the small number of Costco stations selling E15, sold as Unleaded 88. That fuel contains more than 10% and up to 15% ethanol and carries a separate orange EPA warning label. More on those stations below.
Our own data can't answer this one. Our price feed has fields for E10 and "unleaded 91", but as of our September 29, 2026 reading not one of the 593 US or 78 Canadian Costco stations in our cache reports a value in either. The feed only separates regular, premium and diesel, so ethanol content is something you read at the pump, not in any price list.
Is Costco gas ethanol free?
No. We found no Costco in the US that sells an ethanol-free (E0) grade, and Costco's fuel pages do not mention one. Its US pages list regular, premium and, at some stations, diesel. None of those is advertised as ethanol free. One caveat: the code behind costco.com's warehouse pages includes a "0% Ethanol" fuel label, which suggests Costco's locator can show an ethanol-free grade somewhere. We could not find a warehouse that displays it, so check your warehouse's gas section on costco.com before you rule it out.
Does Costco premium have ethanol too?
In the US, assume yes. Costco's statement about ethanol covered Kirkland Signature Gasoline in general, not just regular, and we found no US Costco that sells premium as ethanol free. Our guide to Costco gas grades explains that the only difference between the grades is octane.
A few states do let premium skip ethanol. Oregon, for example, requires at least 10% ethanol in gasoline but exempts gasoline with an octane rating of 91 or higher (ORS 646.913). That is why ethanol-free premium exists at some stations in some markets. We found no source saying any Oregon Costco sells ethanol-free premium, so treat the pump label as the answer.
Why does nearly all US gas contain ethanol?
Three reasons, in roughly this order:
- The Renewable Fuel Standard. Congress created it in the Energy Policy Act of 2005 and expanded it in 2007. It requires a minimum volume of renewable fuel in US transportation fuel each year, and blending ethanol into gasoline is the main way refiners and blenders meet it.
- Oxygenate. When states banned MTBE in the 2000s over groundwater contamination, EIA says ethanol "quickly replaced MTBE as a gasoline oxygenate across the country."
- Octane. Ethanol has a high octane rating, so blenders use it to bring cheaper base gasoline up to 87 or 91. The Alternative Fuels Data Center (AFDC) lists octane, air quality and the RFS as the reasons most US gasoline contains up to 10% ethanol.
The upshot: a Costco without ethanol would be the odd one out, not the other way around.
Does Costco sell E15 or E85?
E85: no, as far as we can find. We found no Costco station anywhere listing E85, and Costco's pages never mention it. E15: yes, at a few Midwest warehouses.
The first Costco to add E15 was in La Vista, Nebraska, according to ethanol trade group Growth Energy, whose staffer publicised it in 2025. GasBuddy's listing for the La Vista Costco now shows Regular, Premium and UNL88. In Iowa, GasBuddy lists only Premium and UNL88 at the West Des Moines Costco and the Ankeny Costco, which suggests E15 has replaced E10 as the cheaper grade there. GasBuddy listings are crowdsourced, so check the pump.
State law is pushing this. Iowa's E15 access standard, passed in 2022, requires most existing fuel retailers to sell E15 from at least one dispenser by January 1, 2026, unless they qualify for a waiver. Nebraska passed a similar law in 2023. Our price feed labels the cheapest grade "regular" at every station, so at these Iowa and Nebraska warehouses the price you see on our Iowa and Nebraska pages may be for E15. As of our September 29, 2026 reading, the four Iowa Costcos we track listed their cheapest grade at $4.03 to $4.15 a gallon, against a US Costco average of $4.64 for regular.
Can I buy E15 at Costco in summer?
Usually, at the stations that carry it. Summer E15 sales used to be restricted by federal vapour-pressure rules. Since April 28, 2025, the EPA has allowed year-round E15 in Illinois, Iowa, Minnesota, Missouri, Nebraska and Wisconsin, with Ohio and South Dakota granted a one-year delay. For the rest of the country, the EPA issued its fifth straight summer emergency waiver on March 25, 2026, effective May 1, which it said it would extend in 20-day steps. The US House passed a bill for permanent nationwide year-round E15 on May 13, 2026; as of September 2026 it had not passed the Senate. We found no source saying Costco has stated a position on any of this.
E0 vs E10 vs E15 vs E85
| Fuel | Ethanol content | Who can use it | Mileage vs ethanol-free gas | At Costco? |
|---|---|---|---|---|
| E0 (ethanol-free) | None | Any gasoline engine | Baseline | None found |
| E10 | Up to 10% | Any gasoline car; most small engines rated for it | About 3% to 4% fewer mpg | Yes, standard at almost every station |
| E15 (Unleaded 88) | 10.5% to 15% | Cars and light trucks model year 2001 and newer, and flex-fuel vehicles | About 4% to 5% fewer mpg | A few Midwest stations |
| E85 (flex fuel) | 51% to 83% | Flex-fuel vehicles only | About 15% to 27% fewer mpg | No |
Sources: EPA and AFDC for E15 approval, AFDC for the E85 range, fueleconomy.gov for mileage.
Does ethanol lower your mileage?
A little. Ethanol holds about a third less energy than gasoline, so fueleconomy.gov says drivers typically get 3% to 4% fewer miles per gallon on E10 and 4% to 5% fewer on E15 than on pure gasoline. EIA puts the E10 figure at about 3%. Natural Resources Canada has found that E10 contains 97% of the energy of pure gasoline, which lines up.
In practice, that 3% is smaller than the price gap between Costco and most nearby stations, and ethanol-free gas usually costs well above regular. For why Costco is cheaper in the first place, see why Costco gas is so cheap. Ethanol also has nothing to do with fuel quality: our post on whether Costco gas is Top Tier covers the detergent additive.
Who should avoid ethanol, and where to find ethanol-free gas
Any car built for gasoline in the last few decades runs fine on E10, and automakers approve it. The engines that struggle are the ones that sit for months or were built before ethanol was common:
- Boats and marine engines. Ethanol absorbs water. Once it holds too much, it "phase separates": the water-and-ethanol mix drops to the bottom of the tank where the pickup is, and the engine sputters or stalls. Maine's environmental department warns that separated fuel is unusable and that E10 can attack some older tanks, including pre-1984 fiberglass.
- Stored small engines. Mowers, generators, chainsaws and snowblowers that sit all winter. Our post on filling gas cans at Costco covers the basics: Costco regular (E10) is acceptable to engine makers such as Briggs & Stratton, but buy about a 30-day supply and add a stabilizer if it will sit longer.
- Classic cars. Older rubber hoses, seals and carburettors were not designed for ethanol. Many owners pay extra for E0.
- Anything with a "no E15" warning. The EPA prohibits E15 in motorcycles, boats, snowmobiles, off-road equipment and cars older than model year 2001. If your warehouse sells Unleaded 88, don't put it in a can for the mower.
A stabilizer slows fuel ageing but does not reverse phase separation. For long storage, keeping the tank nearly full, leaving a little room for expansion, reduces the moist air that gets in.
To find ethanol-free gas, pure-gas.org is the best-known crowdsourced list of ethanol-free stations in the US and Canada. Marinas often sell it, and some branded stations sell ethanol-free premium where state law allows. Call ahead, because listings go stale.
Does Canadian Costco gas have ethanol?
Yes, usually. Canada requires renewable content in gasoline at both the federal and provincial level, so ethanol is the norm at Canadian gas bars too.
- Federal: The Clean Fuel Regulations keep the old Renewable Fuels Regulations' floor: primary suppliers must average at least 5% low-carbon fuel content in the gasoline they produce or import. The old regulations were repealed on September 30, 2024, with the 5% rule carried into the new ones.
- Provinces: Many set higher minimums. These are averages across a supplier's volume, not a per-litre rule, so an individual pump can be higher or lower.
| Province | Minimum renewable content in gasoline |
|---|---|
| Ontario | 11% from 2025, rising to 13% in 2028 and 15% in 2030 |
| Quebec | 10% from 2023, rising to 15% by 2030 (USDA reports a 12% step from 2025) |
| Manitoba | 10% ethanol |
| Saskatchewan | 7.5% ethanol |
| Alberta | 5% renewable alcohol (annual average) |
| British Columbia | 5% renewable, under the Low Carbon Fuel Standard |
| Federal floor | 5% average |
Ontario's figures come from the province's own page, updated September 14, 2026. The others come from a USDA Foreign Agricultural Service report on Canada and the Canadian Press, which has reported that E15 "isn't widely available in Canada."
Is Costco gas ethanol free in Canada?
Regular is not. Premium is the grey area. Over the years, Canadian forum members have reported Costco premium testing ethanol free in Alberta and Ontario, and one RedFlagDeals poster shared an email from Costco saying its premium had no ethanol. Other members report "up to 10% ethanol" labels appearing on premium pumps, and a Northern Ontario tourism group noted in 2023 that some Shell and Canadian Tire stations had added ethanol labels to their 91 pumps as Ontario's rules tightened. Costco Canada's gasoline pages say nothing about ethanol either way.
So the honest answer is: unknown, and likely to vary by province and supplier. If you need ethanol-free fuel for a snowmobile or boat, read the premium pump label at your gas bar, or ask the attendant, before filling. Our newcomer's guide to Costco gas in Canada covers how Canadian gas bars work.
US vs Canada at a glance
| US Costco gas | Canadian Costco gas bar | |
|---|---|---|
| Regular | E10 (up to 10%), E15 at a few Midwest stations | Ethanol blend, usually up to 10% |
| Premium | Treated as E10 | Varies; some members report ethanol free, labels differ |
| Ethanol-free grade | None found | Not advertised |
| E85 | Not sold | Not sold |
| Main rule | Federal Renewable Fuel Standard, state mandates | Federal Clean Fuel Regulations (5% floor), provincial mandates up to 11% or more |
| Where to check | Pump label | Pump label |
Prices differ as much as the rules. For that side of the comparison, see Costco gas in Canada vs the US, or look up any station from the home page, the US hub or the Canada hub.
Frequently asked questions
Does Costco sell non-ethanol gas?
Almost certainly not at your Costco. We found no Costco in the US or Canada that advertises an ethanol-free grade, though costco.com's warehouse pages have a label for one, so check your warehouse's gas section. For E0 fuel, use pure-gas.org or a local marina.
Can I use Costco gas in my lawn mower or boat?
Costco regular is E10, which most small-engine makers accept, including Briggs & Stratton. Boats and stored equipment are more sensitive to water and phase separation, so buy small amounts, add a stabilizer, and never use E15 in them.
Does Costco gas have more ethanol than Shell or Chevron?
No. Costco regular is E10 like most US gasoline, and the ethanol is blended from the same terminal supply other stations use. The difference between brands is mainly the detergent additive, not ethanol.
Is E15 at Costco safe for my car?
The EPA approves E15 for cars, SUVs and light trucks from model year 2001 and newer, and for flex-fuel vehicles. It is not approved for motorcycles, boats, small engines or older cars, so check your owner's manual if unsure.
Can a flex-fuel vehicle use Costco gas?
Yes. Flex-fuel vehicles run on any mix of gasoline and ethanol up to E85, so E10 or E15 from Costco is fine. Costco does not sell E85 itself.
How do I know how much ethanol is in the gas I'm buying?
Read the pump. Costco says the ethanol content label is on the dispenser, and E15 pumps must carry an orange EPA label. The label shows the maximum, and the actual amount can be lower.
Does ethanol-free gas get better mileage than Costco gas?
Slightly. E10 delivers roughly 3% to 4% fewer miles per gallon than pure gasoline, according to fueleconomy.gov. Ethanol-free gas usually costs more than that difference is worth for everyday driving.
Sources
- Gasoline Question and Answer, Costco (Internet Archive copy, February 27, 2025) — Costco's statement that Kirkland Signature gasoline contains ethanol to comply with the RFS, pump label, ethanol-compatible filters; the live page returned 404 on September 30, 2026.
- How much ethanol is in gasoline, U.S. EIA — most US gasoline is E10, about 3% lower fuel economy on E10, E15 for 2001 and newer vehicles.
- Ethanol explained: use of ethanol, U.S. EIA — MTBE replacement, RFS history, E85 for flex-fuel vehicles only.
- Ethanol Blends and E15, Alternative Fuels Data Center (DOE) and E15 — reasons for E10, E85 at 51% to 83%, E15 definition, approved and prohibited uses, about 3,000 E15 stations.
- Ethanol, fueleconomy.gov — energy content and mpg impact of E10, E15 and E85.
- EPA approves nationwide E15, news release, US EPA (March 25, 2026) — 2026 summer emergency waiver, effective May 1, 20-day windows.
- EPA Approves Year-Round E15 Sales in 8 States, CSP Daily News and EPA to implement year-round E15 in Midwest states, DTN — the eight states, April 28, 2025 start, Ohio and South Dakota delay (seen in search results).
- Permanent year-round E15 legislation passes U.S. House, Rep. Michelle Fischbach and Ensure Year-Round Sales of E15, Growth Energy — House passage in May 2026, Senate status in September 2026 (seen in search results).
- GasBuddy station listings for Costco La Vista, NE, West Des Moines, IA and Ankeny, IA — UNL88 (E15) offered at these Costcos.
- A Perfect Time for E15, Advanced BioFuels USA — La Vista described as the first Costco to offer Unleaded 88 (seen in search results).
- Iowa gas stations face 2026 deadline to offer E15, The Gazette and LB 562, E15 Access Standard Act, Nebraska Department of Agriculture — state E15 access laws (seen in search results).
- ORS 646.913, Oregon Revised Statutes — Oregon's 10% ethanol rule and exemption for 91+ octane gasoline.
- Ethanol Fuel and Your Boat, Maine DEP (2010) — phase separation, tank compatibility, storage advice for boaters.
- Cleaner transportation fuels, Government of Ontario — Ontario's 11%, 13% and 15% renewable content schedule.
- Canada: Biofuels Annual, USDA Foreign Agricultural Service (December 2024) — federal 5% floor under the Clean Fuel Regulations, RFR repeal, provincial mandates for BC, Alberta, Saskatchewan, Manitoba and Quebec.
- What are the Clean Fuel Regulations, Government of Canada — the CFR replaced the Renewable Fuels Regulations.
- Fact File: As U.S. approves E15 fuel for the summer, here's what to know about ethanol gas in Canada, The Canadian Press — E15 not widely available in Canada, provincial rates, NRCan finding that E10 has 97% of gasoline's energy (seen in search results).
- Ethanol, Canadian Fuels Association — E10 widely used in Canada, check pump labels, E15 caution for small engines.
- Important Update on Gasoline Ethanol Content, Northern Ontario Tourist Outfitters (2023) — ethanol labels added to some Ontario 91 pumps.
- Has Costco changed their premium gas?, RedFlagDeals forums — member reports on Costco Canada premium and ethanol (forum, seen in search results).
- Pure-gas.org — crowdsourced locator for ethanol-free gasoline in the US and Canada.