Key Takeaways

  • It is not recommended to mix ethanol and ethanol free gas.
  • Ethanol is a biofuel that is often blended with gasoline to reduce emissions.
  • Ethanol has an affinity towards water.
  • Ethanol is a type of alcohol that is produced by fermenting and distilling grains.
  • Octane rating is a measure of a fuel’s ability to stop ‘knocking’ or ‘pinging’

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Ethanol gas and non-ethanol gas are two very different substances. So can you mix ethanol and non ethanol gas in your car?

It is not recommended to mix ethanol and ethanol free gas as it can have adverse effects on the engine and fuel system. However, in a pinch, you can blend both ethanol and ethanol free gas in your vehicle.

I’m a mechanic with five years of experience diagnosing and repairing vehicles. I received my associate’s degree in automotive repair and have over 40 credit hours of studying advanced engine diagnostics. I am ASE certified and still receive training on the latest automotive technologies. I also use the latest tools and technology to diagnose and repair vehicles.

Table of Contents

Mixing Ethanol and Non-Ethanol Gas

It is generally not recommended to mix ethanol and pure gasoline or ethanol free gas, since it can have adverse effects on your engine and fuel delivery system. Ethanol is a biofuel that is often blended with gasoline to reduce emissions and improve a car's gas mileage performance.

However, ethanol has an affinity towards water, meaning it can absorb it. When ethanol absorbs water, the water can then be delivered to the fuel delivery system, which can lead to corrosion inside the system.

Does ethanol clog fuel injectors? No, but the corrosion ethanol causes can. Your car’s gas tank can also get corroded due to water that’s absorbed by the ethanol.

This water in the fuel system leads to fuel delivery system corrosion. This is especially true in older vehicles and vehicles that don’t get driven often. If you mix ethanol and ethanol free fuel, the ethanol can absorb water that may be present in non-ethanol gasoline.

This water absorption can lead to a damaged fuel delivery system. In addition, mixing different types of gasoline can affect an engine’s performance. Different blends of gasoline have different octane ratings, which can affect the engine’s ability to run smoothly and efficiently.

Using the two different gasses can also cause altered gas mileage.

Therefore, it's generally recommended to stick to one type of gasoline instead of mixing the two, unless specified by the manufacturer.

If you need to switch from one type of gasoline to the other, it's recommended to use up as much as the old fuel as possible, before refilling with the new type.

What Is Ethanol?

Ethanol is a type of alcohol that is produced by fermenting and distilling grains, fruits, or vegetables that contain sugar and starch. It is commonly used as a biofuel, a solvent, a disinfectant, and an ingredient in many consumer products including alcohol, beverages, personal care products, and cleaning agents.

In the United States, ethanol is mostly produced from corn and is commonly used as a fuel additive in gasoline to increase the fuel’s octane rating. Ethanol blended gasoline is available at most gas stations and is typically labeled with the percentage of ethanol it contains.

Ethanol gas is labeled E10 such as 10% ethanol, or E15 (15% Ethanol).

Ethanol is considered a renewable energy source because it is produced from plant-based materials that can be grown and harvested again. However there are concerns about the environmental impacts of producing large quantities of corn based ethanol, including its impact on land use and water resources.

How Mixing Gasses Can Harm A Vehicle

Mixing ethanol and ethanol free gasses can potentially harm a vehicle in a number of ways.

  1. Fuel delivery system damage: Ethanol can cause damage to certain types of fuel system components such as fuel tank material, rubber seals, fuel lines, and gaskets. If a vehicle is designed to use non-ethanol gas and it is regularly filled with ethanol blend, the ethanol can cause components in the car’s fuel delivery system to deteriorate.This can affect the car’s fuel system negatively and cause fuel system corrosion.
  2. Engine damage: Ethanol has a lower energy content than gasoline when put in internal combustion engines.  Ethanol gasoline blends may result in reduced fuel efficiency and lower power output. In addition, ethanol has different combustion characteristics than gasoline. This different combustion can lead to a clogged fuel filter and engine deposits.
  3. Water absorption: Ethanol has the ability to absorb water from the atmosphere, which can lead to the formation of corrosive acids and other contaminants in the fuel system. This can cause rust and corrosion in fuel system components, leading to leaks and other problems.
  4. Cold weather performance: Ethanol can also cause problems in cold weather, as it has a higher vapor pressure than gasoline, which can lead to vapor lock and other fuel system issues in cold temperatures.

In general, it's best to use the gasoline according to the vehicle manufacturer’s recommendation. It's best to do this to ensure your engine’s proper performance and to avoid potential damage.

What Is An Octane Rating?

When you arrive at a gas station, you may notice that the gasoline pump offers different octane ratings for fuel. The numbers 87, 89, or 91 may seem arbitrary but they actually represent an important part of gasoline quality: the octane rating.

Octane rating is a measure of a fuel’s ability to stop ‘knocking’ or ‘pinging’ during combustion, which is a rattling or knocking sound that can be heard in some internal combustion engines. Knocking occurs when combustion happens unevenly and spontaneously, rather than being ignited by the spark plug at the correct time.

Higher octane gasoline is designed to resist knocking better than lower octane gasoline. This is important because knocking can cause engine damage over time. For example, knocking can cause piston damage, valve damage, or even damage to the engine's cylinder head.

Octane rating is determined by comparing the performance of a fuel to a mixture of two reference fuels: iso-octane, which has an octane rating of 100, and heptane, which has an octane rating of 0. The octane rating of a fuel is the percentage of iso-octane in the reference fuel mixture that produces the same knocking behavior as the fuel being tested.

Most gasoline sold in the United States has an octane rating of 87, 89, or 91. Some high-performance or turbocharged engines may require higher-octane gasoline, such as 93, to prevent knocking and maintain optimal performance. However, using higher-octane gasoline than what is recommended by the manufacturer does not provide any benefits in terms of fuel efficiency, power output, or engine lifespan.

It is also important to note that octane rating is not an indication of gasoline quality or cleanliness. All gasoline sold in the United States must meet certain minimum standards for quality, including limits on the amount of contaminants and additives allowed in the fuel. Gasoline that meets these standards should be suitable for use in most vehicles, regardless of its octane rating.

Can You Mix Ethanol And Non-Ethanol Gas In Your Car?

About The Author

Christopher Sparks

Christopher Sparks

Christopher Sparks has been servicing vehicles since 2012. After completing the automotive studies program at Camden County College, he was awarded an Associates's Degree in Applied Science. His first job was a lube-tech at Jiffy Lube, and is currently an independent B-Technician servicing vehicles for the United States Postal Service. Christopher is ASE certified and loves rebuilding engines.

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