What to Do If You Accidentally Fueled Your Car with E10 Ethanol?

Fuel efficiency in America has evolved, with E10 ethanol becoming the norm. Many drivers have no choice but to use this fuel, while others opt for higher ethanol blends for Flex-Fuel vehicles designed to operate on a range of ethanol concentrations.

Understanding E10 Fuel

Modern fuel-injected vehicles are engineered to run on E10, a blend of 10% ethanol and 90% unleaded gasoline. If you accidentally fill up with E10 and your car was previously on E-0 (pure unleaded gasoline), you may notice a small reduction in fuel efficiency, typically around 3-4%, but it's highly unlikely that you'll notice any significant differences.

Immediate Steps to Take

The first thing to do when you realize you've filled up with E10 is to go into the office and pay for the fuel. Once you've settled the charges, you can safely drive your vehicle without any need for further action.

However, if your vehicle is a diesel, you face a different set of challenges. In this case, you should immediately call a tow truck and a mechanic to address the potential issues with your engine.

Handling Your Car Post-E10 Fueling

For most vehicles, especially those that are 99% of the norm, E10 is now and has been the standard for decades. Nearly any car that operates on gasoline can successfully run on E10 without any significant issues. Gas stations rarely offer unblended gasoline, and even where it is available, it tends to be the most expensive option.

Flex-Fuel vehicles, which use electronics to optimize their running parameters based on the fuel composition, can still safely operate on E10. However, if your car has been modified to run only on E85 or some other special fuel, it's possible that regular gas could cause knocking or pinging, leading to severe engine damage.

On the other hand, diesel engines are even more sensitive to fuel blends. If you accidentally put any gasoline blend in a diesel engine, you risk serious engine failure due to the high-pressure fuel pump, injectors, and cylinder scoring, among other issues.

What Happens Next?

After addressing any immediate concerns, you can safely drive your vehicle to your destination. E10 will function perfectly in your car, so you should expect no issues going forward. However, if this is the first time you've encountered this problem, it's a good idea to familiarize yourself with the fuel system in your vehicle.

It's worth noting that as long as your vehicle isn't an older model like the Pinto or Studebaker, you are generally safe. Modern cars are designed to handle E10, and even newer blends like E15 are reasonably manageable for most cars that are at least a decade old.

While E15 is a newer blend and may see a slight reduction in performance, most cars from the last 10-15 years can still handle it without issues.