Seth Keighley, of Foster, is met by his mom, Gail, left, and his godmother, Heather Dolan, of Providence, yesterday. The Providence Journal Gretchen Ertl

PROVIDENCE — How far could you get on greasy fried foods?

A pickup truck driven by a Ponaganset High School science teacher and three teens made it all the way to Los Angeles on recycled cooking oil.

That’s because the oil had been converted to biodiesel, a fuel that will power current diesel engines without modification.

“The vehicle handled really great,” teacher Ross McCurdy said when the group marked its return to Rhode Island yesterday at Roger Williams Park.

“We had one catastrophic problem,” said Zane Lewis, a former Ponaganset student. “It was a headlight. We had to change it.”

The foursome left Rhode Island two weeks ago with the truck’s tank full of biodiesel and three reserve tanks holding 250 gallons in the bed of the pickup.

“That was plenty of fuel to get us all the way to California, right down to the water,” said Wylie Smith, another former student.

“We did this to demonstrate that biodiesel is a viable fuel that’s easy to use and it works and it’s reliable,” said McCurdy.

“If we can drive across the country and back with no problems, you can put it in your car and drive to work, no problem, 10 miles,” said Lewis. “Pretty much anybody with a diesel engine can use it.”

McCurdy explained that the used cooking oil is treated with chemicals: methanol, a type of alcohol, and either sodium hydroxide, the main ingredient in drain cleaners, or potassium hydroxide. That removes the glycerine from the oil, allowing it to flow through a vehicle’s fuel system.

They made the coast-to-coast-to-coast trip in a 1997 GMC pickup truck that had been donated by Con Edison Solutions, an energy supplier with headquarters in White Plains, N.Y. The cab had two rows of seats, allowing two people to sleep in back while the other two drove and navigated.

The trip turned out to be more than simply a demonstration of biodiesel, though. The travelers saw a big slice of America.

“There were probably about 50 in ‘coolest things we saw,’ ” said Lewis.

For him, one of the coolest things was one of the hottest: the deserts of the Southwest. “You put your hands outside of the truck, and it’s hotter than it is inside the truck, and that was about 100 inside the truck, maybe 110.”

Among his favorites, Smith listed the Northern California coast. “You had the ocean, then you also had big pastures filled with cattle grazing, with horses, but then you also had the mountains behind you.”

Seth Keighley, who will be a senior at Ponaganset this year, was left virtually speechless by one stop.

“Speed Week at Bonneville Salt Flats,” he said. “Oh, man.”

The teens stood within a few feet of hotrods as they roared off the starting line and accelerated to speeds over 300 mph.

They even got to take the biodiesel truck out on the salt flats — a portion with a speed limit of 55.

pparker@projo.com