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 talk about how much ethanol is in gasoline with different octane ratings. Let’s start with a quick answer:
In the United States, gasoline with an octane rating between 87 – 93 has 10 or 15% ethanol. These types of gasoline are referred to as E-10 and E-15. On the other hand, E-85 typically has an octane rating of 94 or higher.
However, that doesn’t answer the question wholly. Below, we’ll first explain how much ethanol is in each type of gasoline more thoroughly. We’ll also discuss why these percentages are chosen and why this number has increased. Furthermore, we’ll also discuss how much ethanol is in E-85 and the differences between E10, E15, and E85. Finally, we’ll see which type of gasoline is best for your car. Read on!
How Much Ethanol Is In Each Type Of Gasoline And Why?
As we said in our introduction, gasoline with an octane rating of 87, 88, 89, 90, 91, 92, or 93 has an ethanol percentage of 10 or 15%. However, why does the gasoline sold not contain a lower or higher rate, and why did we settle at these numbers
Cleaner Than Regular Gasoline
Ethanol is mixed into gasoline because it is cleaner than gasoline entirely made from gasoline. Congress first mandated the use of ethanol in gasoline in 1990 in the Clean Air Act, and in 2005 Congress passed the Renewable Fuel Standard, which meant a minimum level of ethanol had to be present in gasoline.
However, contrary to popular belief, there’s no scientific evidence for ethanol burning cleaner than regular gasoline. Scientific studies so far have been inconclusive. However, we know that creating ethanol (made out of plants such as sugar cane and corn) is much cleaner to produce. Furthermore, the plants take up CO2 when they’re growing, which means that ethanol is 40% cleaner than regular gasoline on a lifecycle basis.
Politically Motivated
Furthermore, E-10 and E-15 have existed ever since they were introduced because it creates many jobs. For example, Iowa can trace $5 billion per year and 47,000 jobs back to ethanol production for gasoline. Since Iowa is a critical state, political candidates have been sure to promote ethanol in gasoline.
Changing regulations
Politics are also the reason why both E-10 and E-15 exist. When ethanol was first introduced in gasoline in 1990, it started with 10% ethanol.
However, in 2007 Congress raised the levels of the Renewable Energy Standard (which they had signed in 2005). This meant that they aimed to sell 36 billion gallons of ethanol by 2022. As a result, carmakers were forced to start creating cars that we could run on 15% ethanol instead of the 10% they used before.
When you read the owners manuals of different generations of the same car, owners manuals created after 2012 will say that the car is suitable for 15% ethanol whereas before it was 10%.
Can 87 – 93 Octane Also Be E-85?
One thing we’ve failed to mention so far is the existence of E-85 gasoline. As the name suggests, this is gasoline with a much higher ethanol percentage than regular E-10 or E-15. However, it doesn’t have 85% in the United States.
In other parts of the world, E-85 generally does have 85% ethanol. However, in North America, E-85 has to be adjusted for seasonal differences (otherwise, cars wouldn’t start because ethanol is difficult to ignite at low temperatures).
E-85 sold in the United States has 51 – 83% ethanol, depending on the region and time of year. But does this also mean it can be an 87 – 93 octane gasoline?
The chance of E-85 having an octane level below 93 is very slim. This is because ethanol has an octane rating of 100 – 113. For simplicity, the ethanol we use has an octane rating of 100.
Manufacturers of gasoline then have to mix this with regular or premium gasoline with an octane rating between 87 – 95. Our ethanol has 49% regular gasoline with an octane of 87 and 51% ethanol with an octane of 100.