Can You Mix E85 With Regular Gas?: A Complete Guide to Fuel Mixtures

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The question “Can you mix E85 with regular gas?” crosses the minds of most car owners who aim to improve engine efficiency and minimize gas costs. However, you first have to find out if it is possible, and what the implications are. Messing with your car’s fuel can lead to drastic consequences if not done properly.

Can You Mix E85 With Regular Gas


Keep reading as we give you a deep insight into E85 and regular gas and if it’s possible to mix both fuels together.

Can You Safely Mix E85 With Regular Gas?

Yes, you can safely mix E85 with regular gas. Generally, nothing serious happens when you mix the two fuels, but this mixture is only fit for flex fuel vehicles. You will need to double-check your gas car manual for the fuel requirements to be sure that this mix is safe.

This is because while some flex-fuel cars can operate on various fuel blends, some do not allow mixing. The first approach to vehicle maintenance is using suitable fuel. Otherwise, prepare to replace your engine as a result of knocking. But can you mix E85 with 87 gas? If you’ve read this far, you’ve probably longed for answers to this question. 

For clarity’s sake, 87, in this case, does not denote ethanol concentration but the octane number of regular gas. Now let’s see how it’s possible to mix these fuels and what effects you might see in your car after doing this.

– Effects of Mixing E85 With Regular Gas

Mixing these fuels does not significantly impact the engine’s horsepower and performance. If this mix is used in non-flex-fuel vehicles, there is a high tendency for the engine to knock. This is because these vehicles’ engines cannot handle high ethanol concentrations. 

Therefore, filling them with a mix of E85 and regular gas results in rapid corrosion of the fuel system. This can cause injectors and gaskets leakage, which is not so easy to repair. This answers the question “What happens if you mix E85 and regular gas?”

While mixing E85 and regular gas is safe, there are guidelines to follow to preserve your vehicle’s engine. It would be best to avoid excess ethanol in the mix because it can absorb moisture from the atmosphere, causing fuel separation and eventual engine pinging. To be on the safer side, mix both fuels in equal proportions to maintain optimum engine efficiency.

– Advantages of E85 Fuel Over Regular Gas

Here are the advantages of using E85 fuel over regular gas:

Advantages of E85 Fuel Over Regular Gas

  • E85 limits air pollution
  • Dependence on foreign oil is limited
  • The pump price is lower than regular gas
  • It reduces engine tremors
  • It burns cooler
  • It combusts faster, thus increasing engine performance
  • It is renewable and made from natural products

– Disadvantages of E85 Fuel Over Regular Gas

On the other hand, here are the advantages of using E85 fuel over regular gas:

  • E85 is not suitable for all vehicles
  • You can’t get E85 in all fuel stations due to its limited availability
  • E85 attracts moisture, so it has the potential to corrode your engine
  • It has lesser fuel efficiency
  • It’s incompatible with non-metallic materials

– Flex Fuel Vehicles

A flex-fuel vehicle operates on 100 percent ethanol or a mix of ethanol E85 and regular gas, with a higher concentration of the former. Ethanol fuel is common in the US because it’s renewable and has a mild emission of dangerous gasses. In fact, data has shown that the use of Ethanol fuel in the US increased by over 80 percent between 2001 and 2020.  

All automobiles are designed with specified engine maintenance and fuel requirements. More specifically, some vehicles require a blend of ethanol and gasoline to function optimally. Most flex-fuel vehicles operate on E85 fuels, but variations and limits may differ depending on the brand. 

Below are some examples of flex-fuel vehicles, listed according to their brands:

    • Ford: E-series, Explorer, Taurus, Expedition, Ranger, F150 (2WD and 4WD), Focus, Transit, Grand Marquis, etc.
    • Jaguar Land Rover: XJ, Range Rover, XF, Range Rover Sport, etc. 
    • Mercedes-Benz: E-Class W212, C-Class W204, CLA-Class 4MATIC, ML-Class W166, C-Class W20, etc.
    • Toyota: Tundra, Corolla hybrid, and Sequoia.
  • Chrysler Corporation: Avenger, Durango, Renegade, Aspen, Cherokee, Challenger, Dart, etc. 
  • Audi: A5 and A4.
  • General Motors: GMC Sierra 4WD, Equinox, Hummer-H2, SRX, Buick Regal, Avalanche, Chevrolet Malibu, Uplander, HHR, Impala, Silverado (2WD and 4WD), etc.

There are consequences if you use beyond the required ethanol limit. Your engine can either knock or ping. Flex-fuel vehicles are most preferred in limiting GHG emissions, and another advantage is better economical fuel management.

All you need for peak efficiency is an accurate blend of ethanol and regular gas, and your engine is ready to move. Remember we mentioned earlier that E85 is a limited availability fuel. So what happens to these vehicles when there is scarcity? Interestingly, flex-fuel vehicle engines have broad compatibility and can also operate with gasoline or other fuel mixtures; but erase the thought of diesel in this case. 

There are various ways to identify flex fuel vehicles. First, these vehicles usually come with a yellow gas cap or a label on the fuel tank’s door that shows “flex fuel.” Also, the “flex fuel” label may be on the car’s body, or you can find E85 or FFV badges. If you don’t notice any of this, the final method is to check the car owner’s manual for fuel requirements. Note that you shouldn’t fuel your car with E85 if you can’t find any of the mentioned markers. 

– E85 Fuel

E85, also called flex-fuel, is a blend of ethanol and gasoline. While most people mistake the 85 for the octane number of the fuel, it’s definitely not. Ethanol is mixed in various proportions to suit different engines. A general assumption is that E85 is a mix of ethanol and gasoline in 85 percent and 15 percent ratios, respectively.  

However, any fuel termed E85 can contain between 51 to 85 percent ethanol. Note that the ethanol concentration can vary across locations and seasons. E85 contains more ethanol than a regular gasoline engine can accommodate. Many car owners prefer the E85 because it is renewable and limits oil reliance. 

The renewable character is because ethanol is obtained from living organisms, mainly fermented plants. The ethanol source is generally from plant materials, especially corn and grasses. Also, manure and algae are sources of ethanol.

Another reason is that E85 generates fewer greenhouse gasses (GHGs) than gasoline. As a result, cars that use this fuel cause less air pollution. However, it’s more costly than regular gasoline in terms of consumption and can be scarce in some regions.

E85 is not fit for all engines; it’s designed for flex-fuel vehicles. If this fuel is used in non-flex fuel automobiles, the engine risks knocking or a reduced life span. Non-flex fuel vehicles accommodate regular or premium gas and diesel. Other ethanol blends with additives include E5, E7, E10, E15, and E20. Recall that these numbers represent the percentage concentration of ethanol in the mix.

Octane Rating of E85 vs Regular Gas

As mentioned earlier, many people assume 85 to be the fuel’s octane number, but that’s incorrect. Now that we’ve explained what the figure in E85 means, let’s find out its octane rating and significance. 

Octane Rating of E85 vs Regular Gas

The octane rating of E85 is between 100 and 105, and it’s notably the highest of all fuels. Comparing this with regular and premium gas, whose ratings are 87 and 91 to 94, respectively, E85 fuel performs better. This is because the octane number or rating indicates the level of fuel stability. 

Generally, fuel stability has a direct relationship with octane numbers. As a result, the higher the fuel’s octane number, the higher the stability and performance. Also, the octane number measures a fuel’s resistance to compression. Hence, E85 fuel will be your best bet if your vehicle runs a high-compression engine because there is less tendency for untimely detonation, unlike low-octane fuels.

You’ll need an ethanol meter to measure the concentration of ethanol in the fuel mixture. Recall that most of the time, E85 does not necessarily mean 85 percent ethanol. It can vary between 51 and 85 percent, depending on the blend.

– Ethanol Source of E85

The United States is a major ethanol producer. In the last year, over 20 states have produced this fuel. This is because the US is rich in one of the primary sources of ethanol, in this case, corn. 

Keep in mind that local farmers cultivate the corn used in the manufacture. Therefore, other countries have no control regarding the supply of raw materials for fuel production. With these details, it’s obvious that ethanol is a national treasure whose production contributes to job creation for US citizens. 

Data from the Renewable Fuel Association in 2020 showed that ethanol production created over 50,000 jobs. Interestingly, these jobs pay more than the minimum wage, positively influencing the country’s economy. Also, ethanol production contributes $30 billion to the US gross domestic product (GDP). 

As mentioned earlier, the US is rich in corn; thus, it’s the country’s primary plant source of ethanol. You can produce ethanol from corn via dry and wet milling. However, dry milling is mostly used because it’s economical.

– Mixing E85 With Premium Gas

Now that you know what happens when you mix E85 with regular gas, another question that probably strikes your thought is, “can you mix E85 with premium gas?” Premium gas has octane numbers between 91 and 94; like regular gas, you can mix it with E85. Also, mixing these fuels doesn’t significantly influence engine performance. 

While it is theoretically possible to mix these fuels, you should know that not all vehicles are the same. In simple terms, some vehicles will react negatively to fuel combinations. In any case, confirm from the manufacturer specifications and instructions that the car will support mixing fuels. This answers the question “Can you mix E85 and premium gas?”

– Mixing Regular Gas With Premium Gas

Considering that you can mix E85 with either premium or regular gas, the next thought that probably crosses your mind is if you can combine these non-ethanol gasses.

Mixing Regular Gas With Premium Gas

Like other fuel mixtures discussed above, it’s possible to mix regular and premium gas. The two are gasoline but with different octane numbers, as you may have noticed in previous sections. 

Recall that regular gas has a lesser octane value than premium gas. However, if your vehicle is designed strictly for premium gas, it would be best to stick to it. This is because other fuels or fuel mixtures can cause your engine to knock.

What Are the Differences Between E85 vs. Regular Gas?

The main difference between E85 vs regular gas can be seen in the effect on the engine, the fuel economy, the environmental effect, energy generation, and the cost of both fuels. Judging from both fuels’ octane values, it’s safe to say they also differ in performance.

Regular gas is the most common fuel you’ll find in many gas stations in the US, including midgrade and premium gas. Among these three, regular gas has the least octane number at 87, implying lower stability. On the other hand, E85 is not so common; but it has a higher octane number, as mentioned earlier. 

However, aside from the octane number, more differences are discussed below, so keep reading.

– Effects on the Engine

Regular gas is more engine-friendly compared to ethanol, and this is because ethanol can potentially cause adverse effects on vehicle engines. Ethanol in E85 can absorb water from the air, causing fuel separation and impeding engine efficiency if not quickly noticed. Also, ethanol can corrode the fuel tank and other distribution systems, leading to leakage over time.

Fuel Economy

If you’re bothered about fuel efficiency, you should consider regular gas because it lasts longer than E85. The reason is that the latter needs extra burning energy, reducing the gas mileage. Also, this causes the engine’s work to be strenuous. So if your vehicle runs on E85, expect to refill your tank frequently.

– Environmental Effect

E85 has a minimal adverse effect on the environment unlike regular gas. This is because E85 has the least generation carbon footprint. For this reason, many people are looking for how to switch from regular gas to E85 vehicles. As we mentioned earlier, corn is a significant source of ethanol, and producing from this source results in less GHGs emissions. 

Environmental Effect of Fuel Gas

According to a 2021 study by the US Argonne National Laboratory, ethanol from corn releases less than 50 percent GHGs compared to regular gas. One of the reasons E85 has a less toxic effect is the absence of additives like polycyclic aromatic hydrocarbons (PAHs). 

These additives are not necessary for the manufacturer of E85 because it already has a high octane number. However, in most cases, gasoline producers add PAHs to improve octane value. These PAHs are environmental toxins, making the air unsafe for humans. 

– Energy Generation

E85 produces more energy than regular gas due to its increased latent evaporation heat. Hence, when E85 fuel changes state to a gas, the heat absorbed from combustion increases. This characteristic and the high octane number make E85 detonation and knock-resistant.

– Cost

The pump price and cost of producing ethanol are lower than regular gas. However, judging from the fact that E85 burns faster, your refill frequency increases, thus causing you to spend more on fuel. 

On the flip side, E85 burns much cleaner than regular gas. As a result, there are no clogs in the engine and the fuel and exhaust system. Therefore, the engine’s performance is preserved, and maintenance costs are reduced.

Frequently Asked Questions

1. Is E85 Better for My Car Engine Than Regular Gas?

Yes, E85 is better for your car engine than regular gas. Aside from making extra power for the engine thanks to its high octane level, the fuel burns cleaner. As a result, the engine, fuel line piston, valve stems, piston rings, combustion chamber, and injectors lifespans are preserved. 

This is because there are no clog deposits as you’ll find in vehicles running on regular gasoline, thanks to the cleaning effect of ethanol. Interestingly, with E85, you don’t need an injector cleaner. E85 is safe to use on all compatible vehicles.

2. Can I Replace E85 With Regular Gas in My Flex Fuel Car?

Yes, you can replace E85 with regular gas in your flex fuel car. Even though E85 is specially designed for flex fuel vehicles, these vehicles can still operate well on regular gas or other fuels with different octane values as well.

This is because flex fuel vehicles are equipped with sensors that detect the fuel type and adjust for optimum performance. On the flip side, filling a non-flex fuel vehicle with E85 can be detrimental, with a high tendency of engine knock. 

How about using oil? Ordinarily, E85 shouldn’t affect oil consumption. However, recall that E85 can absorb water from the air, so oil mixed with this fuel appears milky and possibly contaminated with water. Impure E85 can produce some compounds that can limit the lubricant effect of the oil. Also, while E85 burns faster, the sump may collect unused fuel, resulting in the dilution of the oil. Therefore, if your vehicle runs on E85, do well to service your engine frequently to limit the occurrence of fuel dilution.


Vehicle maintenance can be challenging, especially if you don’t know how to improve engine performance. However, if you read this guide to the end, you should know the dos and don’ts of fueling your car.

  • You can safely mix E85 with regular gas, but you will have to check your car’s specifications to see how tolerant it will be of mixes such as this.
  • E85 is more eco-friendly than regular gas, which means it is better for the environment than other types of fuels.
  • E85 is designed for flex fuel vehicles and burns faster than gasoline.
  • Some flex fuel vehicles can run on regular gas, so it is best to check for manufacturer’s guides before making any drastic changes.

Take note that using the wrong fuel for your vehicle can lead to various adverse effects, including causing your engine to ping, detonate, or knock. Therefore, whether you already have a car or are about to get one, double-check the fuel requirements to avoid adverse effects.


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