Ethanol in Fuel: Why You Should Care

Depending on your driving habits, you may purchase gasoline a couple of times a week or more. While you may be selective about what gas station you patronize, have you thought about the composition of the gasoline going into your tank? Maybe you’ve glanced at the ethanol sign on the pump, but do you know what that percentage means? Premium synthetic lubricant manufacturer, Royal Purple, wants motorists to be knowledgeable about ethanol, how it can affect your vehicle, and what can be done to combat problems associated with blended fuels.


Ethanol is a 200-proof grain alcohol typically derived from corn. It was first added to gasoline in trace amounts beginning in 1979. Today, nearly all gasoline pumped at gas stations across the country is a mixture of 90-percent gasoline and 10-percent ethanol or E10. Other common blends include E15, or 15-percent ethanol blended gasoline and E85, or 85-percent ethanol blended gasoline.

Common Ethanol Fuel Blends in the United States

  • ·        E10
The most common ethanol fuel blend in the U.S.; 90-percent gasoline, 10-percent ethanol
  • ·        E15
Higher concentration of ethanol-blended gasoline; 85-percent gasoline, 15-percent ethanol
  • ·        E85
Available only at select fueling stations across the country; 10-percent gasoline 85-percent ethanol

Originally, ethanol was incorporated into gasoline as an environmentally-responsible and cost-effective way to reduce carbon monoxide emissions and boost octane. Today, most modern cars do not need ethanol enriched fuels since they are manufactured with sophisticated systems that monitor and continually adjust engine operation to minimize emissions. Ethanol, however, remains a cost effective way for gasoline producers to reduce retail cost, achieve emissions targets and reduce dependence on fossil fuel-derived gasoline.


The effects of ethanol are not limited to gasoline powered cars, motorcycles and trucks. It can also damage occasional or seasonal items such as boats, ATVs, snowmobiles, generators and lawn equipment. As in alcohol, ethanol is hygroscopic, meaning it attracts and absorbs water. When water is introduced into a vehicle’s fuel system it causes rust and corrosion to form on the metal surfaces of the fuel tank and fuel lines. Over time, tiny bits and pieces of corrosion break away from surfaces, and cause clogging of fuel injectors/carburetors, resulting in reduced performance, hard starts, and possible engine problems.

What you may not know is that the oxidation and emulsion effects of ethanol-containing fuel both begin from the moment the fuel is added to the car. This “aeration effect” occurs as you are filling your tank, introducing copious amounts of oxygen and moisture from the air.

Factors that affect the rate at which ethanol-containing gasoline emulsifies and oxidizes include:

  • ·         Humidity levels – particularly for boats in a humid marine environment
  • ·         Temperature
  • ·         Ethanol content
  • ·         Initial fuel quality
  • ·         How full the tank is – tanks that contain less fuel have more air, and air contains oxygen and moisture that drives the oxidation and emulsion processes.

Regardless of how long the gasoline stays in the tank, oxidation and emulsion are always happening to one degree or another. Every vehicle on the road passes non-combustible byproducts of ethanol oxidation and emulsion through its fuel system. Over time, these by-products build and form deposits.

So how does all of this affect your vehicle? If the deposits are left untreated they become “hot spots” that promote detonation. To prevent this from occurring, modern cars with computer-controlled ignition systems must slow down the timing in the combustion chambers that can result in reduced performance, loss of horsepower and diminished fuel economy.

For cars and trucks manufactured before 2001 and especially classic vehicles, ethanol can have an even greater negative effect. Older vehicles were not engineered for E10 or higher blends of ethanol and are not equipped with alcohol-resistant fuel system parts. Over time, ethanol can degrade rubber and plastic hoses and seals, gumming up fuel lines and impacting an engine’s reliability, or potentially cause dangerous fuel leaks.


There are a number of ways vehicle owners can combat the problems caused by ethanol. Owners with older vehicles can replace fuel system parts prone to breakdown from contact with ethanol, such as rubber and plastic fuel lines and o-rings. These parts should be replaced with modern ethanol-compatible components typically manufactured from special grades of nylon and neoprene. You should also replace fuel filters containing paper elements with filters designed for flex-fuel, ethanol-blended applications.

Vehicles and seasonal or occasional use vehicles being stored for an extended period of time should consider using a fuel stabilizer to prevent phase separation.

One easy and convenient way to combat the effects of ethanol found in blended-pump gasoline is to use Royal Purple’s Max-Clean. A state-of-the-art high performance synthetic fuel system cleaner and fuel stabilizer, it provides numerous benefits to combat and protect from the effects of ethanol. It is the only product currently on the market that provides dual benefits of ethanol stabilization and deposit removal, all in a single product.

“Any product we put our name on is the best that can be offered on the market,” said Chris Barker, Royal Purple Technical Services Manager. “Max-Clean is the best fuel system cleaner you can buy and in addition, you get added benefits like a premium fuel stabilizer that will address issues that ethanol in gasoline can create,” he added.

As a fuel stabilizer Max-Clean prevents emulsion and oxidation. It contains demulsifiers that allow already phase-separated fuel to be combusted without doing harm. Max-Clean also contains rust inhibitors that protect metals against corrosion and powerful detergents that will fully remove the deposits that form in fuel systems, regardless if the vehicle is used as a daily driver or stored during the off season.

The next time you go to the pump to fill your tank or gas can, take note of the percent ethanol that the fuel contains. Taking preventative steps to combat the effects of ethanol will protect your vehicle for years to come.

For more information about Royal Purple’s Max-Clean, or Royal Purple’s complete line of synthetic products, visit


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One Comment

  • I appreciated it when you shared that ethanol in gasoline can cause rubber and plastic hoses and seals to degrade over time. Besides, it can cause possible engine problems in the long run. I would like to think if a company needs to get gasoline, it should consider opting for the one without ethanol.

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