What Octane Rating Is E85

Have you ever heard of E85 fuel? If you’re a car enthusiast or just someone who is curious about alternative fuel options, then you may have come across this term. E85 is a type of fuel that is a blend of ethanol and gasoline, and it has become increasingly popular in recent years due to its potential to reduce greenhouse gas emissions.

However, before you decide to fill up your tank with E85, it’s important to understand its octane rating. Octane rating is a measure of a fuel’s ability to resist ‘knocking’or ‘pinging’during combustion. Knocking is a phenomenon that occurs when the air/fuel mixture in the engine’s cylinders ignites prematurely, causing a sharp noise and potentially damaging the engine.

Higher octane fuels are more resistant to knocking, making them ideal for high-performance engines or engines with high compression ratios. In this article, we’ll explore what octane rating is and how it applies to E85 fuel. We’ll also discuss the pros and cons of using E85, so you can make an informed decision about whether it’s the right choice for your vehicle.

Understanding Octane Ratings

So, you might be wondering, what exactly do octane ratings mean and how do they affect the performance of your vehicle?

Octane rating is a measure of the fuel’s ability to resist ‘knocking’ or detonation caused by the air/fuel mixture inside the engine. The higher the octane rating, the more resistant the fuel is to knocking.

Octane ratings are measured using two different methods: Research Octane Number (RON) and Motor Octane Number (MON). RON is the most commonly used method and is the rating you see at the gas station. MON is a rating that is measured at higher engine speeds and temperatures, and is not commonly used.

It’s important to note that octane ratings are not the same as cetane ratings. Cetane ratings measure a fuel’s ignition delay, which is important for diesel engines. The higher the cetane rating, the quicker the fuel ignites and the smoother the engine runs.

However, for gasoline engines, octane ratings are the important factor to consider when deciding on fuel.

Comparing Octane Ratings of Gasoline and E85

When comparing gasoline and E85, there’s a noticeable difference in their ability to prevent engine knocking. Octane rating is the measure of a fuel’s ability to resist knocking. Gasoline typically has an octane rating of 87-93, while E85 has an octane rating of 105.

However, it’s important to note that the octane rating of E85 is not entirely due to its ethanol content, but rather its unique combustion characteristics. Ethanol content is a key factor in the octane rating of E85, but it’s not the only one.

Ethanol has a higher octane rating than gasoline, which means that adding ethanol to gasoline can increase its octane rating. However, E85 is not simply a blend of gasoline and ethanol. The combustion characteristics of E85 are also different than those of gasoline, which allows for a higher compression ratio without causing engine knocking.

This is why E85 is commonly used in high-performance engines, as it allows for more power to be produced without damaging the engine.

Is E85 Suitable for Your Vehicle?

If you own a vehicle, you may be wondering if E85 is a suitable fuel option for it based on its unique combustion characteristics and ethanol content. E85 is a blend of ethanol and gasoline, with ethanol content ranging from 51% to 83%, depending on the season and region.

Ethanol has a higher octane rating than gasoline, which means that E85 has a higher octane rating than regular gasoline. However, E85 also has lower energy content, which means that you may need to refuel more frequently compared to gasoline.

E85 compatibility varies by vehicle model and year, so it is important to check with your manufacturer to see if your car can run on E85. Some vehicles are designed to run on E85, but others require engine modifications to handle the higher ethanol content.

If your vehicle is not designed to run on E85, using this fuel can cause damage to your engine and void your warranty. It’s essential to check your owner’s manual and consult with a qualified mechanic before switching to E85.

Pros and Cons of Using E85

If you’re considering using E85 fuel in your vehicle, it’s important to weigh the pros and cons.

One potential benefit is the positive impact on the environment due to lower emissions.

However, it’s important to note that fuel efficiency may decrease and availability and cost may vary by location.

Additionally, engine performance may be affected by the use of E85.

Environmental Benefits

The environmental benefits of using E85 are significant and cannot be ignored. As a renewable energy source, E85 is much cleaner than fossil fuels. It reduces the carbon footprint, which is the amount of carbon dioxide released into the atmosphere by burning fossil fuels.

By using E85, you can contribute to reducing greenhouse gas emissions, which have a direct impact on global warming and climate change. Furthermore, using E85 supports domestic agriculture. E85 is made from corn, which is a crop that is grown in the United States.

By using E85, you can support farmers in your country and help them sustain their livelihoods. This, in turn, helps to boost the local economy. It also reduces the nation’s dependence on foreign oil, which is a strategic advantage. So, if you’re looking for a way to reduce your carbon footprint and support domestic agriculture, E85 is a great option.

Fuel Efficiency

One of the advantages of using E85 is that it can maximize the mileage of flex-fuel vehicles. This is because E85 contains a higher percentage of ethanol, which has a higher octane rating than gasoline. As a result, the engine can run more efficiently and at higher compression ratios, leading to better fuel economy.

However, it’s worth noting that the actual mileage improvement will depend on various factors, such as driving habits, vehicle type, and weather conditions.

Aside from improving mileage, E85 also has an impact on engine longevity. Due to its higher octane rating, E85 can reduce engine knock and pre-ignition, which can cause damage to the engine over time. This is particularly important for high-performance engines that require a higher octane rating to operate efficiently.

However, it’s important to note that not all engines are designed to run on E85, and using it in a non-flex-fuel vehicle can cause severe damage to the engine. Therefore, it’s important to consult the owner’s manual or a qualified mechanic before using E85 in your vehicle.

Availability and Cost

You’ll be pleased to know that finding E85 fuel stations near you is becoming increasingly easier and more cost-effective. As the demand for this renewable fuel source grows, more and more gas stations are offering E85 as an option for consumers.

In fact, you may be surprised at just how many E85 fuel stations there are in your local area. However, it’s important to note that regional availability may differ. While some areas may have a plethora of E85 fuel stations, others may have very few or none at all.

Additionally, the cost effectiveness of using E85 may vary depending on your location. In some regions, E85 may be priced competitively with traditional gasoline, while in others it may be more expensive. It’s important to do your research and compare prices before deciding if E85 is the right choice for you.

Engine Performance

Improving your vehicle’s fuel efficiency and reducing emissions can be achieved by using E85, but it’s important to consider how it may affect your engine’s performance.

E85 has a lower energy content than gasoline, which means that you’ll need to use more of it to travel the same distance. This can result in lower fuel economy, but the savings from the lower cost of E85 can offset this.

However, not all engines are compatible with E85, so it’s important to check with your vehicle manufacturer to ensure that your engine can handle this fuel. In terms of engine compatibility, it’s important to note that not all engines can handle E85 due to its higher ethanol content.

Ethanol can be corrosive to certain engine components, particularly those made of rubber or plastic. Additionally, E85 requires a different air-to-fuel ratio than gasoline, which means that engines not specifically designed for E85 may experience reduced performance.

If your engine is compatible with E85, it may be necessary to have it tuned to optimize its performance with this fuel. Overall, using E85 can be a great way to reduce emissions and save money, but it’s important to weigh the potential impact on your engine’s performance before making the switch.


So, now you know what octane rating is E85, and how it compares to the octane rating of gasoline. E85 has an octane rating of around 105, which is higher than regular gasoline, making it a good option for high-performance vehicles. However, it may not be suitable for all vehicles, so it’s important to check your owner’s manual or consult with a mechanic before using E85.

Using E85 does have its pros and cons, so it’s important to weigh them carefully before making a decision. On the one hand, E85 can be more affordable and environmentally friendly than gasoline. On the other hand, it may not provide as much fuel efficiency and could require more frequent refueling.

Ultimately, the decision to use E85 should be based on your individual needs and circumstances.