Gas/Ethanol Fuels:

  Tank Up!

by Bob Hoffmann, from the March 2001 Newsletter

It irked me immediately when I saw it.  Perhaps you’ve seen it as well: The sign in front of a local Chevron station that read "Prevent expensive engine repairs; buy ethanol-free fuels here." When I lived in Ohio, I usually filled my gas tank with 10% ethanol blends, and had never had a problem with them.  I also liked the fact that my fuel dollars helped feed the farmers who grew the corn from which ethanol was distilled.  Gasoline mixed with ethanol produces less carbon monoxide and smog compared to straight gas.  Finally, since ethanol is produced domestically, and much of our petroleum supply comes from abroad, I was buying locally, so to speak, reducing the trade deficit, and keeping oil rigs out of environmentally sensitive areas.  So when I saw the ethanol-disparaging sign, I stopped my petroleum-consuming means of conveyance at the nearest parking spot and walked in to see Marc, the station owner.  Yes, he was responsible for the sign.  Yes, he claimed, ethanol-blended fuels could damage vehicle engines.

He launched into a litany of ethanol-related problems.  Ethanol oxidizes metal parts, which can result in the clogging of fuel injectors.  Additionally, ethanol has a tremendous ability to attract and absorb water.  This causes performance and mechanical problems.  He mentioned a number of other supposed problems caused by ethanol.

I was skeptical, but he seemed to be presenting his case in a very scientific manner.  "If you claim ethanol is so damaging," I asked, "Why do all automakers allow its use under warranty?"  Simple, he responded; because the Environmental Protection Agency requires the use of ethanol in certain markets, therefore the automakers have to cover it in their warranties.  Indeed, ethanol-blended gas obviously damages engines, because "I get service bulletins on this all the time."

To see if he was having a common misunderstanding in the automotive world, I asked if he wasn’t confusing ethanol with methanol, a much more toxic and corrosive fuel additive.  "They’re both alcohols, aren’t they?" he responded.  I was shocked that a mechanic would be equating the two.

"If you had a glass of ethanol and a glass of methanol, would you drink both?"  I asked.

"I never drink," he responded flatly.  Probably a good thing, I thought, since he doesn’t know the difference.  I finally asked him if he had any proof of his claims.  Where were those service bulletins he was constantly receiving?  He didn’t have any on hand, but if I’d come back later, he’d show me what he could find.

When I returned, he had printed two chapters of Motor Gasolines Technical Review, a publication available on the  Web .  He had highlighted the presumably pertinent passages.  "What about service bulletins?" I asked.  He didn’t have any for me, but suggested that I contact the individual automakers.

So what did the Chevron document contain to support his claims that ethanol blends could damage engines?  In a word, nothing.  Motor Gasolines Technical Review’s chapters on engine systems, including fuel injectors, did not mention ethanol a single time.  The document did mention methanol's "corrosivity and toxicity defects," leading me to believe that this was another case of confusion between ethanol and a similar-sounding, but very different alcohol.  After contacting customer service at Ford and Chrysler, and contacting local GM and Jeep/Nissan dealers, I couldn’t find any service bulletins or other documents claiming that ethanol damages the engines or components of any vehicles.  Typically, service staff remembered hearing of this supposed damage in the past.  Some said that ethanol actually had caused corrosion and deposits on the fuel injectors of early- to mid-1980's cars.  Others said, no, not corrosion, but erosion.  The details varied, but one thing was constant:  The inability to produce supporting documentation.

I then contacted the American Coalition for Ethanol (http://www.ethanol.org/) and spoke with Trevor Guthmiller.  He said that ethanol, besides being an alcohol, could be characterized as a detergent.  It can loosen carbon deposits, particularly in older vehicles, but since many fuels now contain detergents, this effect is not unique to ethanol.  He was very firm that this would not damage engines.  "The fuel filter will capture any loose carbon deposits, so if you switch from leaded gasoline to a detergent fuel, you will eventually have to change your fuel filter."  He also stated that he’d never seen any documentation about ethanol damaging fuel injectors.  "Automakers were cautionary about ethanol fuel blends in the beginning, but after thorough testing, they realized that it wasn’t ethanol that was causing problems," he told me.  "Methanol blends were frequently responsible for engine damage."  Since then, automakers have endorse, without reservation, the use of gasoline blended with up to 10% ethanol.  This is born out by Ford Motor Company’s Technical Article: Ethanol/Methanol Fuel Blends:

Ford Motor Company vehicles should operate normally if the customer uses blends that contain no more than 10% ethanol or a blend that contains no more than 5% methanol with its necessary co-solvents and additives.  If the methanol does not contain the necessary co-solvents & additives, it will damage the vehicle.

Note that Ford’s statement is without qualification in terms of vehicle model, production year, or the presence of fuel injectors.  Also note that a 10% blend is the maximum typically available, so if you buy an ethanol-blended fuel, you don’t have to worry about whether the ethanol concentration is too rich for your vehicle.

What about the claim that automakers allow the use of ethanol blends only because the E.P.A. mandates ethanol blending in certain areas?  There is no such requirement.  According to the Clean Air Act Amendments of 1990, "All gasoline sold in the specified carbon monoxide nonattainment areas during the winter months when the carbon monoxide level is the highest must be oxygenated gasoline with a minimum oxygen content of 2.7 weight percent." There is no requirement for the use of ethanol, ever.  The requirement is simply to use an oxygenated additive, and ethanol is one of several currently available. Chevron itself uses ethanol to oxygenate gasoline in numerous markets, such as Seattle, Spokane, Vancouver, and Portland, while it uses another common oxygenate, MTBE, in other areas.  Incidentally, MTBE is the same additive that the EPA would like banned in motor fuels, as it is contaminating ground water supplies.

What about ethanol’s water-absorbing capabilities?  Yes, water is soluble in ethanol, otherwise you would have to shake your beer to mix the alcohol with the water, and we know what a mess that would make.  In terms of fossil fuels, Chevron states that a gasoline-alcohol blend can dissolve water up to 6000-7000 ppm at 70°F. "When this blend is cooled, both the water and some of the ethanol become insoluble.  The  result, in both cases, is two layers of liquid: an upper ethanol-deficient gasoline layer and a lower ethanol-rich (about 75% ethanol) water layer.  The engine will not run on the water layer." (Chapter 4,   Motor Gasolines Technical Review)

Chevron did not state the likelihood of this degree of contamination.  But they specifically state that ethanol is transported in such a manner as to prevent contamination with water.  While a 10% ethanol-gas blend can dissolve up to 40 times more water than straight gasoline, Trevor Guthmiller of the American Coalition for Ethanol states that it is highly unlikely that gasoline will come into contact with enough water to result in such high concentrations.  This amount of water in your gas tank can stop your car dead, whether or not the gasoline is blended with ethanol.  Because ethanol-blended gasoline can dissolve water, it greatly reduces the chance of fuel-line freeze-up or water accumulation in your gas tank (e.g. due to condensation).  Any water is diluted throughout the fuel and passes through the fuel line and combustion system with little or no compromise in performance.  This effect, says Guthmiller, is responsible for ethanol blends gaining market share in the winter in South Dakota, where he is based.

There are a number of other supposedly negative claims against the use of ethanol in fuel. These claims tend to vaporize with careful research. So you can confidently fill your gas tank with ethanol blends.  They burn cleaner, support American farmers, and reduce the dependence on imported fossil fuels.

Chevron Corporation was asked to comment on technical issues and any policy about anti-ethanol signage at Chevron service stations.  They forwarded the inquiry to the consumer affairs department three weeks before the press deadline, but no response has been forthcoming.

National Geographic article: Ethanol More Energy Efficient Than Thought, Study Says

Does gasoline really go "bad" if you leave it unused for a period of time? Some people are convinced this is just another urban legend, and that people who worry about "old gas" and spend money on fuel stabilizer are wasting psychic energy as well as cash.

Compare stored gasoline with fresh gas. If you notice it is darker or smells sour it is probably bad.

But in fact, gasoline can degrade over time. That can lead to a number of problems, ranging from hard starting, to rough running, to no starting at all.

Here's why

Unlike crude oil, gasoline is a highly refined product brewed to a certain chemical composition with very specific characteristics. One characteristic of gas is volatility, a term used to describe how easily and under what conditions the gas vaporizes so it can be efficiently burned in your car's engine.

The most highly volatile components in gasoline also tend to evaporate over time. As they do, the remaining fuel's volatility and ability to combust properly degrades. The less volatile the fuel, the less effectively it burns in your engine. The result is diminished engine performance. Your engine may still start and run, but it probably won't run as well.

The good news is, once the old gas has been consumed and the tank is topped off with fresh fuel, the problem should cure itself. Evaporation of volatile compounds can be limited by making sure the gas cap is secured tightly. For the same reason, be sure all portable gas containers are sealed tightly as well.

A more serious problem: Oxidation

Hydrocarbons in the gas react with oxygen to produce new compounds that eventually change the chemical composition of the fuel. This leads to gum and varnish deposits in the fuel system.

These deposits and impurities can clog up gas lines and filters, as well the small orifices in a carburetor and the even smaller orifices in a fuel injector. Removing these deposits can be expensive and your vehicle may not run at all or run very poorly until they are removed.

Water contamination

Condensation can form inside your gas tank and lines from heat cycling. Fuels such as E85, which have a high concentration of ethanol alcohol, may be even more susceptible to water contamination, as ethanol likes to draw moisture out of the surrounding air.

Water contamination can be a problem at gas stations with light traffic due to a slightly different kind of heat cycling. The underground storage tanks experience increases and decreases in temperature. This can cause moisture to form and contaminate the fuel. When you fill up at such a station, you're pumping in the water along with the gas. Such low-traffic stations may also have other contaminants in their underground storage tanks, such as rust. They are best avoided when possible.

Water, of course, does not work too well as a fuel in an internal combustion engine. It will cause hard starting and rough running until it's purged from the system. It can also contribute to internal rusting of the gas lines and tank. The resultant scale and small particles can create a true nightmare, sometimes requiring the replacement of the gas lines and tank at considerable expense.

You can reduce the chances of water contamination by keeping your car's gas tank as close to full as possible, especially if the vehicle is going to be left idle for an extended period.

How do you identify bad gas?

One way is to eyeball it. Oxidized fuel often turns darker over time and may even smell sour. You can check stored gasoline by pouring some into a clear glass container and comparing it side-by-side with known fresh gasoline. If your old sample looks noticeably darker than the fresh gas, you have strong evidence the gas has gone bad.

How long does it take for gas to go bad?

That depends on a number of factors. For one, it's hard to know how old the gas you just bought actually is. It may be fresh from the refinery, or it may be a month old already by the time you top off your tank. Some gasoline is mixed with better or more oxidation inhibitors than others.

It's a good rule of thumb to avoid leaving gas in your tank or a storage container for more than a coupe of months, if you can avoid it. 

And if you can't?

If you know gas will sit in your tank or a storage container for a couple months, then it's a wise move to buy some fuel system stabilizer and mix it in with the gasoline. Do it before you put the vehicle into long-term storage or before leaving your lawn equipment fuel containers sitting for the winter. The stabilizer helps prevent oxidation, the biggie that can turn gas into garbage that gunks up your system and leads to expensive repair work.

Using fuel system stabilizer for extended storage is preferable to draining the tank and leaving the system dry. This can cause rubber hoses, gaskets and seals to dry-rot and crack, possibly leading to leaks and even a fire. In addition, a dry system can expose the insides of metal fuel lines and your gas tank to air and moisture, which can lead to or accelerate the formation of rust.

Fuel system stabilizer is not a cure-all and it doesn't last forever. It must be mixed with fresh gas before the vehicle is stored, not added to already old gas. It can slow down the oxidation process and keep gas fresh for as long as 12 to 15 months. If you're going to leave the vehicle parked for longer than that, you may want to drain the tank and refill with fresh fuel before returning the vehicle to service.