Tyson Sandberg is not a vegetarian, but his car is most of the time.

The Army sergeant stationed at Fort Gordon has converted his diesel-powered, black 1998 Volkswagen Beetle to run on vegetable oil.

He said he got the idea from his father, Tyler, a Utah resident who has converted two vehicles to run on the biodegradable fuel.

"It's safer than gasoline and it's free," Sgt. Sandberg said his father told him.

The car uses conventional diesel to crank the vehicle's engine and to later flush the engine before it is shut off.

After the vehicle's engine starts, engine coolant carries heat from the engine to a 15-gallon tank of oil in the car's spare-tire well. Once heated, the oil becomes less viscous, like diesel. With a button on his dashboard, Sgt. Sandberg switches fuels.

"I got into it because I thought it would be fabulous to drive for almost free on somebody's old, used waste that was going to be thrown away," he said.

The first diesel engines were designed to run on peanut oil, said John Goodrum, a professor of biological engineering at the University of Georgia.

Sgt. Sandberg's vehicle burns diesel or vegetable oil "just like your car burns gasoline," Dr. Goodrum said. "With a gasoline car you have a spark plug; with diesel, you have a high-pressure injector and at just the right time instead of making a spark it squirts in a tiny amount of diesel fuel or vegetable oil."

After completing his first conversion Monday, Sgt. Sandberg said his next step is to find a supplier of used cooking oil to fuel his ride. The cleaner the fuel, the better. Some people use oil from fast food restaurants, but the longer the restaurant goes before changing oil, the more food is cooked in the oil and therefore the more impure it is.

That requires a lot of filtering, Sgt. Sandberg said. For his first tank, he bought 10 gallons of unused vegetable oil from Sam's Club for about $3.25 a gallon.

Sgt. Sandberg said he is looking to ask local Chinese restaurants to give him their spent oil. He said it's a win-win situation for both: He gets fuel and the restaurants don't have to pay to have the oil hauled away.

Sgt. Sandberg bought the Beetle off eBay four months ago for $7,000 with the intent of converting it to run on vegetable oil. He bought the conversion kit for about $850.

He said he completed the conversion during the course of three weekends, working a total of eight hours.

"It took three weeks, a total of eight hours ... well, eight hours of work, one hour of swearing," he said.

The car has almost 70,000 miles and its warranty is expired. Many people choose older vehicles to convert to avoid voiding their warranties, and many of the newest diesels are more difficult to convert, according to www.greasecar.com, the company from which Sgt. Sandberg purchased his converter kit.

He said he was told by greasecar.com that his Beetle should make the same 42 miles per gallon off vegetable oil as it would diesel fuel and the ride should be unchanged. But Sgt. Sandberg will go through a tank of diesel much slower than he would normally, without the natural fuel.

The only side effect? The car's exhaust will probably smell of won-tons, egg rolls or french fries.

"I'll never have to worry if there's a fuel shortage,'' he said. "People never stop eating."

Reach J. Scott Trubey at 868-1222, ext. 109, or ccchron@augustachronicle.com.