Gasoline Mysteries Revealed

Following President George Bush's call for clean air legislation, Phillips 66 sent Gary Schoonveld, its senior research engineer, on a 16-city national tour in 1989 to explain gasoline and emissions to audiences of fleet managers and other interested groups.

The whistle-stop tour was so successful that Phillips extended it into 1990 to four additional cities. Chief among Schoonveld's varied audiences were fleet managers, all of whom, he believed, benefited from definitions of such fuel components as octane ratings and additives, and tips on good driving habits for fleet vehicle users.

"I was surprised how little people know about gasoline, a product they use every day," says Schoonveld. "The questions asked were all good questions. It's just that I had expected a greater knowledge of gasoline than there really is."

The answers to those - and other questions - are important, Schoonveld says, because fleet managers who are well-informed about gasoline traits can find new methods to affect cost-saving practices in their day-to-day operations.

How Gasoline Works

Gasoline is a complex chemical liquid produced from crude oil at refineries in a process termed 'cracking.' About 20-22 gallons of gasoline are produced from a barrel of crude oil, Schoonveld estimates, adding that gasolines contain anywhere from a few hundred to a thousand different, complex, chemical structures.

"The properties of the final liquid are those that have been determined as necessary for satisfying engine requirements," Schoonveld says. "Properly refined and blended, they will provide optimum performance in a well-tuned engine."

Among the many different characteristics that come into play during the gasoline combustion process, Schoonveld says, is volatility, which is a measure of how easily gasoline will boil away, or evaporate when left in open air.

Volatility becomes a factor when the liquid is injected into the engine; by the time the piston draws the fuel/air mixture into the combustion chamber, the gasoline must be a vapor. That is why starting a cold engine on a winter's day requires a gasoline that evaporates easily - allowing the engine to start quickly despite the low temperatures, Schoonveld says.

Conversely, gasoline must be less volatile during hot weather to help avoid 'vapor lock,' a condition which occurs when heal creates vaporous bubbles in the fuel line before the gasoline passes through the carburetor or fuel injectors. When 'vapor lock' occurs, the fuel cannot be pumped, thus stopping the engine. The engine must cool down and the fuel re-liquify before attempting to restart.

Schoonveld says gasoline producers alter their blending formulas slightly to match weather changes. Additionally, the producers make adjustments to other components - based on climate changes - to optimize performance and keep the output of emissions to a minimum.

Schoonveld also says that producers follow this practice because it's sensible and the Environmental Protection Agency (EPA) mandates low-volatility fuels to be sold during summer months (May 1 -Sept. 15). Some states even require lower levels than the EPA requires. Both are attempts to reduce evaporative hydrocarbon emissions to the atmosphere.

Is this simply interesting trivia, or useful knowledge that fleet managers can apply? This information is definitely useful, Schoonveld says. Because of the time delays involved in delivering fuels to the consumer, gasoline producers need to adjust their distribution systems to meet the EPA dates. As a result, low-volatility fuels hit the market early in the spring and are phased out later in the fall.

Consequently, fleet operators may receive complaints from drivers about difficulty in starting and warm-up operations when the weather is on the cold side during these distribution periods. Without knowing about volatility additives, fleet managers might otherwise think there was something genuinely wrong with the vehicles.

Part of Schoonveld's job is quality assurance and control. For that reason, gasoline samples are periodically brought into his lab from throughout the nation on which to run tests which assure their compliance for volatility and other gasoline specifications.

What Is Octane?

Octane is a number-rating which designates a gasoline's ability to prevent pre-ignition. Pre-ignition is an undesirable phenomenon that occurs when the gasoline/air mixture explodes, or ignites, spontaneously - before the mixture receives the spark flash from the spark plug. A fleet manager knows pre-ignition is occurring, Schoonveld says, when fleet: drivers report hearing a knocking or pinging sound coming from the engine during acceleration, when climbing a hill, or pulling a heavy load.

The noise, in effect, is alerting the driver that uncontrolled combustion is taking place, and, if the knocking becomes severe enough, the engine can be damaged.

Picking An Octane

Fleet managers frequently ask Schoonveld which octane rating their vehicles should use. In general, he says, higher octane number gasolines are less likely to cause pre-ignition, thus well-tuned engines can perform best when using higher octane gasolines.

Three octane ratings are typically available to fleet drivers: unleaded regular at 87; mid-grade at 89; and premium unleaded at 91 to 93. Most of today's engines, Schoonveld says, are designed to burn gasoline with an 87 octane, except those vehicles with turbochargers, superchargers, and special high-performance engines - all of which require high octane fuels.

What Additives Do

Octane, alone, is not the only solution to ensuring optimum performance, Schoonveld says, which is why gasoline producers put special additives in their gasolines. The types and amounts of these additives vary, but following are some common ingredients: detergents which clean the fuel system, thereby keeping metered changes precise; corrosion inhibitors which prevent deterioration of the metal parts in your fuel systems; dehazers or de-emulsifiers which separate water droplets from fuel; and de-icers, which help prevent carburetors and fuel lines from freezing up.

Most additives are producer-specific formulas that are injected into tank trucks at the supply terminal. Then, the finished, brand name product is delivered to the service outlet. Some the early 1970s, Phillips has put additives into its gasoline, but in 1986, a stronger demand for additives came from consumers as more vehicles began to use sensitive fuel-injection systems.

It didn't take long, Schoonveld says, for people to discover these injection systems would become clogged when using untreated, or improperly-treated gasolines. Sometimes, after driving a new car only 600-1,000 miles problems would crop up, notably engine stalls, general balkiness, and difficult starting. Among manufacturers, General Motors responded first, alerting the gasoline producers that such problems could be cured with additional detergents in the gasolines.

Put on notice, the gasoline producers went back to the laboratory. In 1986, Phillips emerged with a new line of unleaded gasoline products called "SuperClean Gasolines," which contained enhanced detergents. Other companies followed suit.

In modern fleet operations, where the majority of vehicles are equipped with fuel injectors, the most important consideration for the fleet manager is whether the fuel being used can prevent blockage in fuel injectors or clean up the existing deposits which impede performance.

"Gasoline which is properly metered through clean fuel injectors decreases the amount of unburned fuel expelled out the tailpipe," Schoonveld says. "So, clean fuel injectors are the first step in decreasing air-polluting emissions and helping fleets run more efficiently."

Dirt is the biggest enemy to engine efficiency. Proper maintenance begins with timely replacement of filters - not just the oil filter, but also fuel filters, air filters, and those within the emission system.

As an example, Schoonveld offers the air filter, saying, "To burn 15 gallons of gasoline, an engine uses the equivalent of five, 48-foot tractor trailers filled with air. That's a lot of air to move through such a small filter, so if it is partially-blocked with dirt particles, the fuel/air mixture will be altered, resulting in poor gas mileage.

"The larger a fleet, the more money it can save by enhancing fuel economy in every way possible."

Schoonveld says following these good driving habits are beneficial:

• Avoid jackrabit starts, which causes unburned fuel to go out the tailpipe;
• Fuel economy suffers at high speeds because every time speed is doubled, it requires four times the power to overcome wind drag.

What The Future Holds

Alternative fuels being investigated by Phillips include: methanol, propane, and compressed natural gas. Other petroleum companies are exploring the options of electricity, hydrogen, and grain alcohols. Schoonveld says development has been discouraged because of the poor salability of such vehicles, particularly those with special engines, or where fuels are not available on a retail basis.

"If you're a fleet operator in a high pollution area of the country," Schoonveld says, "You may have an opportunity to participate in evaluating the operational and emission benefits of alternative fuels.

"I'm aware of several such fleet programs already in operation. Some are subsidized or operated by governmental bodies, but others have stood alone with systems that are economically feasible.

"For instance, the low cost of liquid petroleum gas, or propane, may make fuel conversion economical for certain fleet operations.

"Gasoline has been optimized to a degree of sophistication which makes it a low polluter with high reliability, but we are working with engine manufacturers and others within the oil industry to identify reformulation concepts for gasoline that may result in even lower emissions."