Diesel Fuel Contamination Affects Colorado Gas Stations

In early January 2026, Colorado state regulators began receiving over 200 complaints from drivers who inadvertently filled their vehicles with diesel fuel instead of regular unleaded gasoline at several gas stations, including Costco, King Soopers, and Murphy Express. The contamination occurred when diesel fuel was mistakenly loaded from the HF Sinclair terminal in Henderson, Colorado, between 2 p.m. on January 7 and 6 a.m. on January 8. State officials confirmed the presence of diesel at multiple locations, prompting an investigation by the Division of Oil and Public Safety.

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The contaminated fuel was reported at various gas stations across the Denver metro area. King Soopers identified several impacted locations, including:

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• 14967 Candelas Pkwy., Arvada

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• 25701 E. Smoky Hill Rd., Aurora

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• 17000 E. Iliff Ave., Aurora

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• 3050 S. Peoria St., Aurora

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• 1045 S. 1st St., Bennett

Here’s where Denver gas stations sold tainted gas

• 12167 Sheridan Blvd., Broomfield

Here’s where Denver gas stations sold tainted gas

• 2355 W. 136th Ave., Broomfield

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• 7284 Lagae Rd., Castle Pines

Here’s where Denver gas stations sold tainted gas

• 750 N. Ridge Rd., Castle Rock

Here’s where Denver gas stations sold tainted gas

• 5125 W. Florida Ave., Denver

Here’s where Denver gas stations sold tainted gas

• 1611 Pace St., Longmont

Here’s where Denver gas stations sold tainted gas

• 12959 S. Parker Rd., Parker

Here’s where Denver gas stations sold tainted gas

• 17761 Cottonwood Dr., Parker

Here’s where Denver gas stations sold tainted gas

While King Soopers initially reported about two dozen affected stations, diagnostics later revealed that several were not contaminated.

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Zach Hope, Petroleum Program Manager for the Division of Oil and Public Safety, stated that the agency is working to determine the cause of the contamination and has not issued fines or enforcement actions, as it appears to be an unintentional error rather than negligence. Sinclair is conducting its own investigation and has communicated with the Colorado Wyoming Petroleum Marketers Association to address the issue.

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Costco and Murphy Express have not provided a comprehensive list of affected locations but have assured customers that they will reimburse expenses related to repairs caused by the contaminated fuel. Customers are encouraged to contact the gas station where they purchased fuel to initiate claims.

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The impact of diesel fuel in gasoline engines can vary. According to Stephen Martindale, service director at Phil Long in Denver, vehicles may stall shortly after fueling if a significant amount of diesel was added. Repair costs for affected vehicles can range from $1,000 to $5,000, depending on the extent of the damage and the vehicle's complexity. Drivers experiencing issues are advised to have their vehicles towed to a repair facility for diagnostics and remediation.

Here’s where Denver gas stations sold tainted gas

Some affected drivers have expressed frustration over the situation, with reports of vehicles stalling and significant repair costs. Kassandra Johnston, a driver who filled up at a King Soopers station, reported her vehicle's performance issues and estimated repair costs starting at $1,300. Concerns have been raised about the speed of the claims process and the potential for widespread impact, leading some to consider filing insurance claims instead.

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The contamination of gasoline with diesel fuel at various Colorado gas stations has prompted a state investigation and raised concerns among affected drivers. As Sinclair and state officials work to resolve the issue, impacted customers are encouraged to file complaints and seek reimbursement for any necessary repairs.

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