In 2011, the United States Environmental Protection Agency (EPA) approved the E15 gas after more than two years of testing to confirm it was safe to use in model-2001 and newer cars and light-duty trucks (1).

More than 90% of cars on U.S. roads are of the model year 2001 and later, and they account for at least 95% of the fuel consumption in the country. But what is E15 gas?

Read on to learn more about this new type of fuel and whether it is safe to use in your car.

What is E15 Gas?

E15 is a fuel composed of 15% ethanol and 85% gasoline. It has 5% more ethanol than E10, the most popular fuel in the United States (2).

Ethanol is a simple alcohol, which, when blended with gasoline, acts as an oxygenate. Federal regulations have allowed the use of ethanol-blended gasoline to lower carbon monoxide, particulate, and hydrocarbon emissions while promoting the use of renewable fuels.

E15 gas has a higher-octane rating of 88 compared to 87 octane rating of E10 gas. Fuel retailers offer E15 gas as Unleaded 88 to emphasize its high-octane rating (3).

According to Dr. Andrew Randolph, former head of advanced engine development at General Motors,

Unleaded 88 provides an octane boost compared to regular 87 octane fuel, which helps modern engines achieve peak performance while reducing costs for the consumer


Regulations require the retailers to display an orange and black E15 label on pumps that distribute gasoline that contains 15% ethanol.

The EPA allows the use of E15 in all model year 2001 vehicles and newer. According to the Renewable Fuels Association, E15 is not appropriate for vehicles built before 2001, light-duty trucks, motorcycles, or medium-duty passenger vehicles. But, is E15 gas harmful to your car? Read on to find out.

Is E15 Appropriate for Your Car?

There’s an ongoing debate about whether the higher ethanol-content of E15 can cause problems to a vehicle. The truth is that automakers have changed the formulation of vulnerable components. Thus, all cars of the model year 2007 and later should be compatible with E15 gas.

In fact, a study conducted at the Kettering University found no notable degradation in fuel systems of vehicles built in 1995 and later (4). There have also been worries about the warranty validity for damages that result from E15 usage.

The truth is that E15 usage won’t necessarily void your car’s warranty. In fact, in 2014, automakers approved more than 70% of their top-selling cars for E15 usage (5). The cars include various makes and models of GM, Ford, Honda, Volkswagen, Land Rover, Jaguar, and Mercedes-Benz.

Gas Station

It’s worth noting that when the EPA approved E15 in 2011, automakers had already written many of their vehicle owners manuals. Thus, these owners’ manuals didn’t address the issue of E15 usage.

Many of today’s owner’s manuals, however, provide guidance on E15 usage. Generally, automakers won’t deny a warranty claim based on the use of a fuel type if that fuel didn’t contribute to the issue for which a car owner makes the warranty claim.

Does E15 Cause Corrosion?

One of the major complaints by E15 opponents is that ethanol can corrode many of the plastics, metals, and rubber components used in internal-combustion engines and their fuel systems. Hence, using fuel with a higher concentration of ethanol than the manufacturer recommends may damage your vehicle.

As we mentioned above, however, automakers changed the formulation of the vulnerable components in the vehicles of the model year 2007 and later. Thus, you can safely use E15 gas if you own a car built in 2007 or later.

For older cars, however, it not a good idea to use E15 as the cars may experience variousissues associated with burning alcohol. You should realize that ethanol absorbs moisture more easily compared to gasoline, which can lead to corrosion-related issuesin fuel tanks and gum up carburetors and filters.

Ethanol can also dissolve rust in the fuel tank, which can end up in the fuel system. You can avoid these problems by installing ethanol-compatible fuel lines, filters, and other components in your old car.

Final Thoughts

Since the EPA’s approval of a new gasoline formula known as E15 in 2011, there’s been an ongoing debate about whether it is okay for use in vehicles. Although regulations don’t recommend using this environmentally-friendly fuel in older vehicles, many studies have found no substantial negative impact of using E15 gas in newer models of cars.

Now that we got this question answered, here are some tips to make your car more eco-friendly and even some bonus home energy-saving tips.