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Can You Mix E-85 And Unleaded Gasoline? (Explained)

Can You Mix E-85 And Unleaded Gasoline? (Explained)

Writing about different types of fuel is a daily practice on this blog. However, we haven’t answered every question yet. Therefore, we will use this blog to discuss if you can mix E-85 with unleaded types of gasoline. Let’s start with a quick answer:

E-85 and unleaded gasoline can only be mixed in Flex-Fuel vehicles. These vehicles can be recognized by the yellow fuel cap and the Flex-Fuel or E-85 marking on the back or sides of the car. Mixing E-85 and unleaded gasoline in vehicles that aren’t Flex-Fuel will damage the fuel system.

However, that doesn’t answer the question wholly. Below, we’ll first explain how to check if your vehicle can take a mix of E-85 and unleaded gasoline without any problems. Furthermore, we’ll explain how to mix these types of gasoline safely and what happens if you do it carelessly. Read on!

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Also read: Why Mixing Different Octane Gasoline May Destroy Your Car

Can You Mix E-85 With Unleaded Gasoline?

Yes, you can mix E-85 with regular or premium unleaded gasoline. However, this is only the case for Flex Fuel vehicles. Not all cars are Flex Fuel vehicles, and you’ll have to check this before jumping in and mixing two different kinds of gasoline.

A Flex-Fuel vehicle can be recognized based on several features. First, these cars generally have a yellow fuel cap with ‘E85 / Gasoline’ written on it. Furthermore, these cars typically have badges on the outside of the vehicle, as displayed in the image below.

Only these types of vehicles can run on E-85. Furthermore, these are also the only types of cars that can run on a mixture of E-85 and other types of unleaded gasoline. If you put E-85 in a vehicle that’s not specifically Flex Fuel, you’ll get a loud knocking noise from the engine. If you continue driving the vehicle at this point, you’ll destroy the fuel system beyond repair.

Should You Mix E-85 With Unleaded Gasoline?

Switching to E-85 from regular or premium gasoline can be a good option. As we established in this article about whether or not E-85 is cheaper than other types of gasoline, we know that that’s not necessarily the case. However, we know that E-85 is a lot cleaner to produce and burn when we look at the complete lifecycle. Switching to E-85 is, therefore, a good idea.

How To Mix E-85 With Unleaded Gasoline?

If you’re planning on mixing E-85 with unleaded gasoline, it’s essential to know that there are wrong ways and proper ways to do this.

Mixing E-58 And Unleaded Gasoline In The Tank Of Your Car

Let’s first discuss how you do this when you want to mix the two types of gasoline in the tank of your car.

First of all, it’s essential to know that car manufacturers suggest you use one type of fuel for a prolonged period. It’s not recommended to switch between unleaded gasoline and E-85 whenever you feel like it.

This is because the fuel system parts get used to a specific type of gasoline, and switching regularly will upset these parts to the point where they’ll break down much faster.

Instead, it’s recommended that you pick a specific type of gasoline and stick with it as long as possible. Some people may want to switch to E-85 when the weather gets warmer, and starting the vehicle with E-85 is easier, and that’s completely fine since this means you change gasoline about twice a year.

When you switch, keep in mind that car manufacturers suggest you fill-up the car with at least 3 gallons of the gasoline you’re planning on using. Furthermore, after filling up, it’s advised to immediately drive the vehicle for at least seven miles. This way, the fuel system can get used to the type of gasoline directly.

Mixing E-85 And Unleaded In A Jerrycan

Another way you can mix E-85 and regular or premium unleaded gasoline is by combining both types of gas in a jerrycan. Maybe you have some excess gas and want to mix it with E-85; who knows. However, is this possible?

Yes, this is entirely possible. For example, you could mix five gallons of E-85 with five gallons of unleaded E-10 gasoline with 87 octane. This will give you a 50/50 split of both types of gasoline. Depending on the percentage of ethanol that’s in the E-85 (typically between 51 – 83% in the United States) and the octane rating it has (typically between 100 – 113), you’ll end up with a mix of gasoline that’s classified as E43 with an octane of at least 93.

However, keep in mind that ethanol goes bad much quicker than regular gasoline. How long ethanol will last in a jerrycan depends on many factors, such as moisture in the air. Typically, ethanol will be fine for at least three months and could last as much as three years.

If you mix these types of fuel and you wonder whether or not the mix of gasoline is still usable after a while, check for these signs that something is wrong:

  • A layer of water at the bottom of the container
  • A reduction in the amount of gas left (this is a sign that evaporation has occurred)

If one of these has occurred, the gasoline mix is probably not usable anymore.

Finally, please store gasoline with a high ethanol percentage in a metal jerrycan since ethanol eats away at plastic over time.

What If You Mix Wrong?

There are a few ways you can mix E-85 and unleaded gasoline in the wrong way. These include:

  • Trying to create an E-10 or E-15 blend of gasoline for a vehicle that’s not Flex-Fuel
  • Mixing too little E-85 or too little E-10/15 in the tank of your car when switching from one to the other.

Trying To Create E-10 Or E-15

Let’s start with the first one. One of the things that are very risky to do is to create E-10 or E-15 by mixing 100% unleaded gasoline with a small percentage of E-85. Some people think about doing this because it may save them a small amount of money.

However, this can destroy your car’s fuel system when done wrong and it’s one of the worst things you can accidently throw in your tank. First, you’ll need to know precisely what amount of ethanol is in your E-85. In the United States, E-85 has 51 – 83% ethanol, depending on the region and the season. Also read: How Much Ethanol In 87 – 93 Octane Gas? (Regular & Premium)

Then, you need to get the quantities right. Let’s assume the blend you’re using has 80% ethanol (E-80). To create E-10, you’ll have to mix one part of your ethanol-gasoline with eight parts of the 100% unleaded gasoline.

If you get this wrong, or if the percentage of ethanol is not correct, you’ll end up with gasoline that will destroy your car’s fuel system since it’s not Flex-Fuel. Instead, buy E-10 or E-15 at certified retailers.

Mixing Too Little Unleaded Gasoline Or E-85 When Switching

However, the most common thing you’ll hear is people mixing too little E-10/15 or E-85 into their tank when switching from one to the other in their Flex-Fuel vehicle. Also read: E-85 vs. E-15 vs. E-10 (All Differences Explained!)

If you mix less than three gallons of the fuel you’re switching to; the engine starts to create a knocking sound. This is because mixing too little of the fuel will result in misfiring of the spark plugs, which will destroy the engine.

If you hear this noise, it’s essential to stop the vehicle immediately and call for assistance. To prevent this, please mix E-85 and unleaded gasoline in the way it’s described in your owner’s manual.

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