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Grease is the word

High gasoline prices are driving more car owners to use discarded vegetable oil as diesel engine fuel

W ELLESLEY -- Michael Cohen is a senior marketing associate for a Fortune 500 company, who lives in a brick and green-clapboard house on a tree-lined lane called Bluebird Road. There are golf clubs in his garage and a gold-tone Mercedes in the driveway. Both his hair and lawn are impeccably trimmed.

Yet while he seems about as counterculture as a Land's End catalog, Cohen can boast of something that would turn even a Birkenstock-clad environmental activist chartreuse with envy. The 44-year-old restaurant supply salesman has nearly achieved a "closed loop" for his personal and business energy consumption, at least as far as transportation is concerned.

The last time he visited a gas station? Two months ago, when he purchased a summer's supply of fuel (worth less than $10) for his lawn mower.

The secret lies beneath the hood of his 1984 Mercedes-Benz 300 Turbo Diesel wagon. About three years ago, Cohen joined a small but steadily growing number of suburban auto owners who have retrofitted their cars to run on used food-grade vegetable oil.

Once considered an oddity favored by gearhead tinkerers and environmentalists, vegetable oil conversions -- a.k.a. "grease cars" -- are gaining in popularity, thanks to concerns about global warming and gasoline prices near the $3-per-gallon mark. Industry insiders say that over the last few years, hundreds in Boston's western suburbs have bought up older diesel autos and had them converted to run on both diesel and vegetable oil.

Those owners are discovering that their grease cars not only get better gas mileage, but also that their emissions are less harmful than their diesel or gasoline counterparts.

And that's not even the best part.

If the car owners can find a cooperative restaurant owner or two willing to part with the waste oil (eateries usually pay about $1 per gallon to have the stuff hauled away), their fuel is basically free.

In Cohen's case, the vegetable oil conversion and his job as a salesman for Sysco Corp., a food-service supply firm, have allowed him to become his own oil company, refinery, and fuel station owner. Each week, Cohen picks up as much as 15 gallons of the vegetable oil he sold to restaurants and cafeterias the week before. He takes it home, runs it through a $10 filter, and uses it to fuel his Mercedes through his sales route again.

"It's empowering to drive past gas stations along the road, and to hear friends of mine who have bought new cars say they cost $80 to fill," he said.

Based on the cost of filters and his 350 miles of weekly driving, Cohen estimates that he saves nearly $2,200 on fuel each year. The kit cost about $850 and paid for itself in the first year, he said.

Cohen used a German-made Elsbett kit, but many of the systems installed by grease car owners in Boston's western suburbs were manufactured by a Massachusetts company, Greasecar Vegetable Fuel Systems ( of Easthampton. The seven-year-old company has sold nearly 4,000 conversion kits, including several hundred to customers in Boston's suburbs.

Justin Carvin, founder of the company, said most of Greasecar's customers are regular folk (albeit somewhat adventurous), not environmental activists or aging hippies.

"We actually tried advertising in Mother Earth News . . . and it was completely fruitless," Carvin said. "As it turns out, our customer analysis shows that our core demographic is actually men in their 50s to 70s who are doing it to save money."

It is that money-saving aspect that has earned grease cars another nickname: "the poor man's Prius." At around $22,000 and 50 to 60 miles per gallon, a new gas-electric hybrid owner might save $400 to $500 per year on fuel, but will likely also have to pay between $500 and $700 in yearly interest on a car loan. A grease car enthusiast can spend $2,000 to $5,000 for an '80s-vintage Mercedes diesel, plus $1,000 to $2,000 for a vegetable oil conversion kit and filtering supplies.

"Diesels have a notoriously long life span and are a much sturdier vehicle," said Jamie Merkle, a schoolteacher and vegetable oil conversion consultant from Hudson who owns two grease cars, a 1987 Mercedes-Benz SDL and a 1998 Volkswagen Jetta TDI. "We have an obsession with new cars. People keep buying new cars and we keep making new cars, and that's just a huge drain on our resources."

Merkle recommends the Greasecar kit, which employs the most popular, two-tank configuration.

The basic kit consists of a heated second fuel tank, a heated fuel filter, several fuel-switching valves, gauges, and control switches. Once installed, it essentially creates a second fuel supply system that addresses the only drawback with vegetable oil -- since it is much thicker than diesel fuel at room temperature, it must be heated before it can be injected into the engine, and purged from the cylinders before the engine is turned off and allowed to cool.

Single-tank kits like Cohen's Elsbett allow for the use of diesel, biodiesel, or vegetable oil, but require more extensive modifications to the car's glow plugs and fuel injectors.

Even with single-tank kits, though, the engines only need minor tweaks to use vegetable oil, because inventor Rudolph Diesel designed the engine to run on a variety of fuels more than a century ago.

Both an inventor and a social theorist, Diesel intended his engine for use not as transportation, but as an industrial power source, one that would level the playing field for smaller-scale manufacturers and commercial farmers who could not afford large, expensive steam engines -- the preferred power source of the day. When Diesel demonstrated his engine at the 1900 Paris World's Fair, he powered it using peanut oil.

While it takes extra steps to run a two-tank car on vegetable oil -- starting the car using regular or biodiesel from the original tank, switching fuels when the vegetable oil reaches the proper temperature, and running a purge cycle before turning the car off -- most owners say they don't mind. And soon they may not have to. Some of the newest kits, including ones from Greasecar and a Seattle firm called Frybrid, include microprocessor-controlled systems that do the switching automatically.

Most owners also say they love the unexpected little bonuses of running a grease car. One example: While sports car owners can tune the sound of their exhaust using aftermarket mufflers, grease car owners can actually tune the smell of their exhaust depending on which fuel they use.

Some swear by using oil that has only been used to cook french fries. Others insist that oil from gourmet Chinese restaurants not only has the best smell, but also the best quality (as it turns out, trans fats not only clog arteries, but fuel injectors as well). Most say that oil that has seen heavy use or been used to cook seafood is best left for use by commercial diesel/vegetable oil delivery trucks. Such vehicles are just starting to catch on in the United States, but are becoming commonplace in the European Union, which has ordered that 5.75 percent of all fuel for trucks and autos must come from renewable sources by 2010.

"I got some lemon oil once as a sample from a supplier and I put it in just for fun," Cohen said. "The smell was absolutely delightful."

Even if having a car that emits smells reminiscent of Burger King is a little weird, grease car owners like 18-year-old Jake Weisberg of Sudbury say they are most proud of what isn't in their exhaust. Vegetable oil produces no sulfur emissions and fewer greenhouse gases than regular diesel. Such fuel is also considered "carbon-neutral," since the plants that the oil was derived from pulled their carbon from the air in the first place.

While their cars would run fine on virgin vegetable oil, used oil is preferred by green-minded grease car owners because little or no extra energy was used to convert it to a fuel.

"They're better for the environment, better for the economy. It's really a win-win," said Weisberg, who converted a 1982 Volkswagen Rabbit two years ago.

Some grease car owners, like Weisberg and Sheila Leavitt of Newton, say they consider their cars to be statements of personal belief. When Leavitt bought her converted 1999 Volkswagen Beetle, she sold "Sam," a 1991 Toyota Corolla that she had hand-painted in bright colors and that sported a black-and-gray rooftop effigy of a dead Uncle Sam meant to symbolize voter fraud in the 2004 presidential election. She said she felt like she could make a different sort of statement with her low-emissions recycled-fuel car.

"It was just time for a change," said Leavitt, an activist for a variety of liberal causes.

Other owners, like Cohen, say they are just trying to adjust to the reality of living on a planet that is running out of increasingly expensive fossil fuels and getting warmer every year.

"I'm not trying to change the world," Cohen said. "I'm just trying to change my world."


What he drives: 1984 Mercedes-Benz 300 Turbo Diesel wagon

What fuels it: Used food-grade vegetable oil

Conversion type: Single-tank Elsbett (German) conversion that allows his car to run only on vegetable oil.

Savings: Cohen drives about 350 miles per week and estimates that he saves about $2,200 on fuel annually, meaning that the $850 conversion kit paid for itself in the first year.


What he drives: A 1987 Mercedes-Benz SDL and a 1998 Volkswagen Jetta TDI

What fuels them: Used food-grade vegetable oil, biodiesel, diesel

Conversion type(s): Custom dual-tank systems that allow both cars to run on either vegetable oil or biodiesel and regular diesel.

Savings: Merkle does not track his fuel usage, but he estimates that it took 10,000 driving miles each for his conversions to pay for themselves.