Sorry GM Drivers, Your Warranty Doesn't Cover This

Let's say you are out running errands in your recently purchased General Motors vehicle when it starts to idle roughly, hesitate, smoke from the tailpipe, or throw up a bunch of trouble lights on the dashboard. Obviously, something fairly serious has gone wrong with the car, but at least you can have some peace of mind knowing the problem will be covered by your warranty, right? 

In normal cases, these sorts of issues would absolutely be covered by the manufacturer. But, as it turns out, that's not always the case. A January 2026 General Motors service bulletin, first spotted by the folks at GM Authority, points out that the manufacturer is not responsible for engine and fuel system damage caused by using contaminated or incorrect fuel. Modern cars can usually run without serious issues on lower-octane fuel than the manufacturer recommends, but pumping gasoline into a diesel vehicle (or vice versa), even once, is a much bigger problem, often resulting in major damage to engines and fueling components. 

These problems aren't always caused by car owners being careless at the gas pump. Sometimes, contaminated or mislabeled fuel can be put into retail pumps by gas suppliers, wreaking havoc on cars through no fault of their drivers. What GM is doing is simply highlighting the reality that fuel quality and contamination are not in its control — and thus not covered by warranty.

When you think of someone accidentally pumping the wrong fuel, the first thing that comes to mind is probably an individual who just forgot what type of vehicle they were driving or otherwise had a lapse of focus while pumping. But on rare occasions, the fuel providers themselves are the ones who mess up. In November 2025, fuel delivery trucks accidentally mixed up which type of fuel went into which pump at a Connecticut gas station, causing tens of thousands of dollars in damage.

However, GM released this service bulletin in response to an even larger fuel labeling mess-up in January 2026. This incident saw more than 50 Sinclair-supplied gas stations in Colorado and Wyoming receive diesel in their gasoline pumps due to Sinclair mistakenly filling diesel into petrol tankers. As of mid-January, the situation had led to around 600 complaints from affected drivers.

As for General Motors, the service bulletin did not represent a change in GM's warranty rules to deny coverage. The company simply issued guidance to its service departments in the event that Colorado customers showed up expecting their warranties to cover damage from the contaminated fuel. And, unlike other controversies where automakers have denied warranty coverage to owners, it's clear and easy to see why GM wouldn't cover this under warranty.

In the service bulletin that GM issued, the company outlines possible symptoms and engine codes the affected vehicles will have, and clarifies that it will not cover repair costs for vehicles affected by contaminated fuel. Nor will customers be eligible for any goodwill assistance from GM, as the mispumped fuel is completely out of their control and not related to any failure of the vehicles themselves. 

However, this doesn't mean that GM is being flippant or thoughtless toward owners who might be affected. The bulletin notes that owners should seek restitution from the fuel station or fuel providers and advises them to keep all repair receipts so that they can be reimbursed. These are common steps for anyone who may have been sold bad fuel.

Fortunately, drivers affected by the Colorado gas contamination issue — GM owners or otherwise — won't be left out of pocket here. Sinclair has since stated that it will take financial responsibility for any necessary repairs. In the meantime, though, just know that if you happen to pump the wrong fuel by mistake, your factory warranty probably won't be of much help when it comes to fixing the damage.