What’s In Your Fuel — The Gov’t Allows More Ethanol In Pump Gas

Ethanol in our pump gas is nothing new. In fact, the current government regulations allow for up to 10-percent of gasoline sold at the pump to be mixed with ethanol. That is, until the summer of 2022, when the EPA issued a Nationwide Fuel Waiver allowing for up to 15-percent of pump fuel’s content to be ethanol. The waiver was extended seven times over the course of the summer, comprising the entirety of the Summer Volatility Control Period (when you get the so-called “summer blend” gasoline).

Ethanol In Fuel

Anyone who has paid attention to the development of ethanol for automotive use knows that besides being cheaper than gasoline, it has a higher octane rating. However, it has a lower energy density than gasoline, so it requires more volume to make the same horsepower. Additionally, ethanol can be detrimental to rubber seals and certain plastic components in an automotive fuel system.

To that end, modern fuel systems are built to withstand up to a 10-percent concentration of ethanol in the fuel, and the vehicle’s ECU is tuned with that taken into account. Although the Department of Energy does say that modern vehicles (2001 and newer) can operate on E15, it also concedes that fuel economy (miles per gallon) is generally lower with increased levels of ethanol in engines that are optimized for gasoline.

In a report published December 1, 2022 by the US Energy Information Administration, it was revealed that as of April 29, 2022, the amount of ethanol allowable in pump gasoline was increased to 15 percent, nationwide. That temporary waiver was effectively made permanent for the entire Summer Volatility Control Period thanks to a total of seven temporary waivers. Additionaly, the report stated that over the summer, all the gasoline in the United States contained an average of 10.5-percent ethanol (which, in and of itself meets the requirements of being called “E15” by the DoE’s definition), which is the highest rate on record.

Average ethanol blend percentages in the US.

In the summer of 2022, more ethanol was blended into US gasoline than ever before.

Reasons For Allowing E15

There are several reasons that E15 was allowed over the summer. First, is that during the pandemic, a significant amount of refining and production capacity was lost. With fuel demand increasing to pre-lockdown levels, further “cutting” of the available fuel supply with readily available ethanol increased the available amount of fuel, just like adding cereal to your meatloaf.

Secondly, ethanol is less expensive than gasoline and its various components. By replacing an additional five percent of gasoline with less expensive ethanol, costs were theoretically reduced. Whether or not those savings made it to the end consumer is a whole different debate, but there was a cost-savings somewhere in the chain.

Ethanol is a less expensive way to boost the octane number of the base fuel, as opposed to refining it to that octane rating without the use of ethanol.

Effects Of E15

As everyone has bemoaned since ethanol was first introduced into pump fuel, it can have some detrimental effects on a vehicle’s fuel system and engine if not accounted for. Since anything above 10-percent ethanol requires special consideration, running E15 in a vehicle not designed for it can lead to a range of issues from a simple mileage decrease on the minor end, to fuel system component damage and detonation issues on the severe end of the spectrum.

For example, for a modern vehicle with active knock sensors and wideband oxygen sensors, the engine will most likely be protected from any damage, and the user will simply notice a decrease in fuel mileage. Short-term effects of an additional five-percent concentration of ethanol should be minimal and unnoticeable, but the longer-term effects are unknown, even though the DoE states that 2001 and newer vehicles are “approved for E15 use”.

This map shows all the different regional fuel specifications as required by law. Plot a cross-country road trip and it’s likely you’ll have quite a few different formulations of fuel in your tank along your route.

At the other extreme, a highly tuned vehicle that runs on pump gas (which a large percentage of our audience has sitting in their driveways right now), which doesn’t have knock sensors, and runs in an open-loop configuration might start to see detonation issues. While that would still be an extreme case, as you would have to be tuned to the absolute edge of safety, it’s a legitimate concern. Not to mention that anything older than the 2001 model-year is listed as “prohibited” from using E15 by the DoE.

Total Seal‘s Lake Speed, Jr. conducted testing at Shaver Specialty with their ultra-reliable test engine, and noticed the difference in power caused by the altered chemistry of the pump fuel. After some A-B testing, it was determined that the issues weren’t brand specific and were likely due to additional ethanol content in the gasoline.

What Do I Do?

If you are reading this in the winter months, there is nothing to be done. This was an issue during “summer-blend” season. However, the cynical side of us says that unless something changes drastically before it starts warming up in 2023, this is likely to take place again. However, now being informed that this is happening, there are steps you can take.

Much like we have advocated for testing the actual concentration of ethanol when you buy E85 from the pump, if you have a performance vehicle running on pump gas, you might want to start performing simple ethanol content testing on the fuel from your local station during the summer months the be sure of what you are getting. Also, you might want to dial back your performance tuneup a little bit, if you are close to the edge now. Giving up a few horsepower to err on the side of safety when using pump gas might not be a bad thing.

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About the author

Greg Acosta

Greg has spent nineteen years and counting in automotive publishing, with most of his work having a very technical focus. Always interested in how things work, he enjoys sharing his passion for automotive technology with the reader.
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