E85 ethanol alchohol
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What Every Motorist Should Know About E85 Gasoline

by Larry Carley copyright AA1Car.com

e85 Chevy Tahoe flex fuel vehicle

Is E85 motor fuel a corny way to reduce American's dependence on foreign oil? E85 is being touted as an eco-friendly, alternative fuel that can provide a home-grown solution to reducing our need for fossil fuels and imported oil.

What is E85?

E85 is a blend of up to 85% ethanol alcohol and 15% gasoline (though during winter months, the percentage of gasoline may be increased to as much as 30% for easier cold weather starting). The alcohol in E85 is ethanol, the same kind of alcohol that is used in Vodka and other alcoholic beverages.

E85 is a high octane fuel with an octane rating that can vary from 100 to 105 depending on the amount of gasoline in the blend, which can vary from 15 to as much as 30 percent or more depending on the season. More gasoline is typically added to the blend during cold weather to improve cold starting.

E85 is an oxygenated fuel that burns cooler and cleaner than gasoline. It can deliver 3 to 4 percent more horsepower compared to gasoline, and up to 8 to 10 percent more horsepower if an engine has been optimized for E85 with a higher compression ratio (14.2 to 1 is the optimum ratio for E85). For this reason, the use of E85 as an alternative racing fuel is growing. E15 is now the fuel of choice for NASCAR, with E85 being used in Indy car racing as well as a growing number of circle track, road racing and drag racing applications. E85 is an environmentally greener fuel compared to leaded racing gasoline or methanol alcohol, and it is considerably cheaper than racing gas.

Ethanol is made primarily from corn, but it can also be made from a variety of starchy or sugary crops including potatoes, sugar cane and beets. In fact, ethanol can be made from anything that contains fermentable sugar, including organic garbage. Gasoline is added to E85 to improve its cold start characteristics and to denature the fuel so it cannot be consumed.

The Renewable Fuel Standard (RFS), which Congress passed in 2005, requires the use of biofuels (such as ethanol) in the U.S. fuel supply. The EPA determines how much ethanol must be blended into gasoline to meet the mandate. Since 2009, most gasoline in the U.S. has contained 10 percent ethanol.

To encourage the use of E85, the federal government gives fuel alcohol producers and retailers some rather significant tax credits. Gas stations that sell E85 receive a federal income tax credit of 51 cents per gallon. Corn growers receive farm subsidies. Alcohol distilleries also get various tax credits and incentives. Even the auto makers get a fuel mileage credit on every flex-fuel vehicle they produce. This helps the auto makers lower their overall Corporate Average Fuel Economy (CAFE) numbers. The CAFE rating on a flex-fuel vehicle is calculated as if it were running on E85 and not gasoline, so only the gasoline portion that is used is figures into the calculation.

Is E85 Cheaper Than Gasoline?

E85 currently sells for about 30 to 70 cents a gallon less than gasoline depending on local pricing and availability. That sounds pretty good, but E85 does not contain as much energy as straight gasoline. Alcohol contains only about 80,000 BTUs per gallon compared to about 120,000 for gasoline. Because of this, the fuel economy you get with E85 is not as good as with gasoline. The fuel mixture requires about 25 percent more fuel so the resulting fuel economy may be 15 to 30 percent less depending on how you drive. The end result is that the cost per mile for E85 is slightly less than that for gasoline. You won't save a bundle but you will be using a renewable fuel that is domestically grown by American farmers and produced by U.S. distillers.

Can E85 be Used in Any Vehicle or Only Flex-Fuel Vehicles?

E85 requires certain modifications to the fuel system, including uses fuel lines, seals and other components that are compatible with high concentrations of ethanol. If E85 is used in a vehicle that is not designed for flex-fuel, fuel system corrosion may occur.

E85 requires a richer fuel mixture than gasoline, typically around 9.7 to 1 compared to 14.7 to 1 for gasoline. Consequently the fuel pump and fuel injectors must be capable of flowing about 50 percent more fuel at higher engine loads and speeds compared to gasoline only.

The engine management system has to know whether or not a vehicle has been fueled with E85, and how much ethanol is in the overall average mixture. If you fill a near empty tank, the fuel will contain 85 percent ethanol and 15 percent gasoline. But if you fill a tank that is only half empty, the resulting mix may be only around 40 to 45 percent ethanol.

On many first generation flex-fuel vehicles (as well as vehicles that have been converted to run on E85 with an aftermarket E85 conversion kit), a special fuel sensor is used to detect the ethanol content of the fuel. The sensor uses a dielectric measuring principle to determine the percentage of ethanol to gasoline (ethanol is more conductive than gasoline). The engine computer then uses the fuel sensor's input to adjust fuel delivery and spark timing according to the concentration of alcohol in the gas.

On some newer flex-fuel vehicles, there is no fuel sensor. The engine computer estimates how much ethanol is in the gasoline based on feedback from the exhaust oxygen sensors and fuel trim adjustments. It will adjust the fuel mixture as needed to achieve the correct air/fuel ratio.

flex-fuel sensor determines ratio of ethanol to gasoline
Flex Fuel Sensor (courtesy Siemens VDO)

What Happens if I Accidentally Fill My Ordinary Vehicle with E85?

If your vehicle is a 2007 model year or newer, it probably won't cause any noticeable problems. If your vehicle is a 2001 model year or newer, the engine will probably run okay but the E85 may cause the Check Engine light to come on. If your vehicle is a 2000 model year or older, it will likely cause some engine roughness and turn on the Check Engine light. See What To Do If You Put The Wrong Fuel In Your Car.

All vehicles made in the U.S. since 1995 are required to have alcohol-resistant fuel systems, so the risk of damaging the rubber or plastic components in your fuel system with a single tank of E85 is minimal. Vehicles built since 2001 are even more resistant to alcohol so for those applications there is probably little or no danger of damaging anything.

Because E85 requires a richer fuel mixture to run properly, you may notice a rough idle or some misfiring when first starting the engine after an accidental refill with E85. The effect will depend how much gasoline was already in your fuel tank when you filled with E85. If the tank was a quarter or half full, the effect will be much less noticeable than if the tank were near empty. In any event, the engine computer will start to compensate immediately for the leaning effect produced by the E85. After driving for a few miles, the computer should be correcting the fuel mixture and there should be little or noticeable change in engine performance. However, because your engine management system was not calibrated to handle the richer fuel mixture that E85 requires, the engine computer may think something is wrong and set a P0171 or P0174 lean code and turn on the Check Engine light.

Some people say you should have your fuel tank drained immediately to avoid any possibility of fuel system damage or engine performance problems. This is usually an unnecessary expense in most instances. Just drive your vehicle normally but with a light foot. No hard acceleration, no towing a trailer, no mountain driving and no prolonged high speed driving until you have used up most of the E85 in your tank.

Depending on the flow capacity of your fuel pump and fuel injectors and how your engine computer is calibrated, your fuel system should be able to deliver the extra flow required by E85 at idle and part throttle. But it may not be able to provide enough fuel at high engine loads and speeds. This would allow the fuel mixture to go dangerously lean, which can result in engine-damaging detonation (spark knock).

If you did not completely fill your fuel tank with E85, top it off with some 87 octane unleaded fuel as soon as possible to help dilute the concentration of ethanol in the fuel tank. If you completely filled with tank with E85 and are worried about the possible consequences, just drive normally until you have used up most of the E85 and refill with gasoline, or refill with gasoline when you have reached half a tank.

How Many Flex-Fuel Vehicles?

General Motors, Ford and Chrysler have all been building "flex fuel" cars and light trucks capable of running on either gasoline or E85 since 1999 to 2000. According to the Renewable Fuels Association (RFA), there are now more than 22 million flex-fuel vehicles on the road in the U.S.

E85 fuel pump

Where Can You Buy E85?

The number of service stations that are currently selling E85 has grown in recent years, so finding E85 is not the challenge it once was. Here are a couple of resources for finding a service station that sells E85:

E85 Locations

Ethanol Retailers

When refueling with E85, the E85 pump may be a separate pump located away from the gasoline pumps, or there may be a separate button on the pump for E85. The handle on the pump is usually color coded YELLOW.

Why Should You Use E85?

Using E85 (or any other ethanol/gasoline blend) as a motor fuel reduces the oil we have import from offshore. The fuel is renewable and can be made from a variety crops. Crude oil is a fixed resource and is becoming increasingly expensive to recover both in drilling costs and environmental costs. The automotive industries in China and India are booming increasing the world's population of vehicles dramatically. The day is coming when there will not be enough oil for all of these vehicles. That's why we need to start shifting to alternative fuels such as E85 and others (including electric and natural gas). You might even consider building a still and brewing your own alcohol fuel.

Geologists estimate the world contains at most about three trillion barrels of recoverable crude oil. We have already used more than a quarter of that amount, and are now sucking oil out of the ground at a rate of 75 million barrels a day. Nearly 80% of this is being burned by various modes of transportation.

Here in this country, we use 15.5 million barrels of oil a day. Of this, about 10 million barrels of oil a day are imported (65% of the total!). One barrel of crude oil typically yields a little more than half a barrel of gasoline, so that translates into a burn rate of roughly 9 million barrels (or 495 million gallons) of gasoline a day!

Ethanol production has grown significantly in recent years. U.S. ethanol production is currently around 900,000 barrels a month. One bushel of corn yields about three gallons of ethanol. Some of this is being used to produce E85 fuel, but most of it is being used as an octane booster and oxygenate in "reformulated" gasoline and premium grade fuels.

Food Versus Fuel?

The use of ethanol made from corn has been rapidly growing rapidly. As more and more new distilleries are being built, production capacity has been expanding. In 1998, about 5 percent of the U.S. corn harvest (526 million bushels) was used to make ethanol according to the National Corn Growers Association. In 2006, that figure had grown to over two billion bushels (nearly 20 percent of the crop). In 2008, U.S ethanol production was pumping out an estimated 23 million gallons of ethanol a day, with a capacity to produce 8 billion gallons of ethanol by year's end. By 2017, U.S. ethanol production had risen to 15.8 billion gallons, with Iowa, Nebraska and Illinois producing over half of the total.

The growing demand for corn to produce ethanol has been fueling a debate of "food versus fuel." As corn prices have doubled, many have blamed soaring food prices on diverting too much corn to fuel production. Many say this is totally false, as current food prices are being driven by an increase in world demand, lower yields in some other grain-producing countries, and the effect of high fuel prices on transportation, manufacturing and packaging costs. Profiteering by middlemen and speculators have had a far greater impact on food prices at the consumer level than using corn to produce ethanol. After all, there's probably less than 10 cents worth of corn in a $4 box of cereal. If the price of corn jumped 50%, that should only add 5 cents to the cost of the end product. But it doesn't work that way. As the price of the commodity gets marked up at each step in the production and distribution process, even a small increase in the price of the raw materials is multiplied many times to inflate the end price of the product. So don't blame ethanol production for rising food prices.

To read more opinions about the food-versus-fuel controversy, see SmarterFuelFuture.org.

Is Your Vehicle a Flex-Fuel Car or Truck?

Carmakers have been building flex-fuel vehicles for almost a decade now. Most of these vehicles have a decal or emblem on the back that indicate they are flex-fuel capable. If you don't know if your vehicle is flex-fuel capable or not, refer to your owners manual. Flex-fuel capability may also be marked on the gas tank filler cap.

flex-fuel yellow gas tank cap
Flex fuel vehicles usually have a yellow gas cap and a FLEXFUEL emblem.

flexfuel emblem
If your vehicle does not have a FLEXFUEL emblem or gas cap, do NOT put E85 in the tank!

E85 Flex Fuel Vehicle Applications

As a general rule, most of the Flex Fuel vehicles that have been offered to date (starting back in 1999) have been domestic pickup trucks (Ford, Chevy, GMC and Dodge Ram), popular SUVs such as Ford Bronco and Explorer, Chevy Tahoe and Suburban, GMC Yukon and Denali, Dodge Dakota and Durango, Jeep Cherokee and Commander, along with Chrysler minivans, Ford Taurus, Mercury Sable, Chrysler 300, Stratus and Sebring, and some Mercedes models.

Up until 2015, auto makers offered about 80 different models that were Flex Fuel capable. But since then, the number of models with this capability have declined, with only Ford and GM offering a limited number of Flex Fuel vehicles in 2022.

The best way to tell if your vehicle can use E85 is to check your gas cap. If it is yellow, you can safely use E85.

Related Articles:

What is E15?

Alternative Fuels

SUVs vs Trees, CO2 Emissions and the Environment

To more Technical Articles Click Here To Read More Automotive Technical Articles

alcohol fuel book cover
How To Make Your Own Alcohol Fuels book on CD

How to build a still and brew your own ethanol fuel

E85 Related Links:

E85Prices (Find E85 prices in your area)

Growth Energy - America's Ethanol Supporters

National Corn Growers Assn.

Renewable Fuels Association (RFA)

U.S. Dept of Energy Alternative Fuels Data Center

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