Young woman standing outside putting gas in her car.

What to do if you put the wrong gas in your car

Pumping the wrong fuel can happen to anyone. Learn about some possible scenarios and solutions in case it happens to you.

When you go to the gas station, you may have access to different fuel types for your car — unleaded or premium gas, diesel or Ethanol E85. What happens if you put the wrong gas in your car? Let’s explore different situations, possible car damage and ways to address it.

What happens if you put diesel in a gas engine?

Diesel pumps are typically a different color and have larger nozzles that usually won't fit into a gasoline tank's opening. But in the case you do put diesel in the tank, your car may not start because gas engines cannot combust diesel. If the car does start, it will probably smoke. While engine damage is unlikely, you might need to have the vehicle towed and get the tank drained — a service that may range from $200 for minor issues to $2,000 for a full flush.

What happens if you put gas in a diesel engine?

Gas nozzles are smaller, so they could fit into a diesel engine tank. If this happens, know that the engine can be impacted by simply turning the key, so try to recognize the mistake before you start the car. Because diesel acts as a lubricant for the fuel system, thinner gasoline can cause the fuel pump, filter and injectors to wear, especially if the engine runs. Call for a tow as soon as possible, and have a professional evaluate the tank for needed drainage and check any impacted parts.

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What happens if you put premium gas in a regular gas car?

This is mostly a matter of preference but refer to your owner's manual for fuel-type recommendations. If you filled your tank with premium gas instead of regular gas, you may not experience any negative changes in the operation of your car.

What happens if you put regular gas in a premium gas car?

If this happens, you may hear rattling and notice reduced performance and decreased fuel economy, but your car probably won't sustain lasting engine damage. Simply switch back to premium as soon as possible. If a vehicle manufacturer recommends premium gas for your car, try to follow their recommendation. Continued use of regular gas in a premium gas engine may affect car performance and could cause engine damage.

What happens if you put ethanol E85 in a gas car?

Ethanol should be clearly labeled at the pump, but grabbing the wrong nozzle can happen. If the car is not a flexible-fuel vehicle (capable of running on gasoline or gasoline-ethanol blends up to 83%), you may see the "check engine" light flicker. But this swap probably won't cause permanent damage. Top off your tank with regular gasoline, and your car should eventually run as normal. Just in case, though, you might want to check your manufacturer warranty to see if using E85 void’s the warranty.

Is misfuelling covered by insurance?

If you've merely added plus/premium to a regular tank or vice versa, you might avoid any resulting damage or financial costs (for an occasional error). But if you need a tank drain or tow, check with your State Farm® agent to see if your insurance covers the damage. Many insurance policies do not cover damage resulting from misfuelling, but some may offer specialty riders that do.

How to avoid choosing the wrong fuel

  • Know your car: Diesel vehicles can use diesel, and that's it. For gasoline cars, check your owner's manual for the minimum octane rating, and see that the fuel you use equals or exceeds that number. Generally, regular gas has an octane level of 87, premium is 91 or 93 and plus falls somewhere in between. Cars that require premium also may specify an octane preference on the gas cap. Some cars may simply have a "recommend" fuel.
  • Consider a misfuelling prevention device for diesel vehicles: You can purchase a diesel fuel tank insert that refuses gas nozzles. Some car manufacturers have started equipping all diesel vehicles with a similar mechanism as a standard feature.
  • Pay attention at the pump: Eliminate distraction at the pump (leave your phone in the car, for example). Carefully review each button and/or nozzle to make sure you know which fuel type you are choosing. Especially when stopping for gas at a new station where the options/placement may vary.

Now that you've learned what may happen if you put the wrong fuel in your car, here are some ideas to help you use less gas, guidance on what to do if your gas pedal sticks and ways to help protect your vehicle from gas theft.

The information in this article was obtained from various sources not associated with State Farm® (including State Farm Mutual Automobile Insurance Company and its subsidiaries and affiliates). While we believe it to be reliable and accurate, we do not warrant the accuracy or reliability of the information. State Farm is not responsible for, and does not endorse or approve, either implicitly or explicitly, the content of any third party sites that might be hyperlinked from this page. The information is not intended to replace manuals, instructions or information provided by a manufacturer or the advice of a qualified professional, or to affect coverage under any applicable insurance policy. These suggestions are not a complete list of every loss control measure. State Farm makes no guarantees of results from use of this information.

State Farm Mutual Automobile Insurance Company
State Farm Indemnity Company
Bloomington, IL

State Farm County Mutual Insurance Company of Texas
Richardson, TX

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