With diesel fuel approaching $4 a gallon in the East Valley, some motorists with diesel engines are converting their vehicles to run on vegetable oil. Charlie Anderson, president of Golden Fuel Systems, said interest in his company's waste vegetable oil conversion kits has soared.
"Every time there's a spike in fuel prices, there's a spike in interest," he said.
Dave Roberson, who runs Alternative Auto Care in Mesa, converted his 1995 Dodge truck to burn the waste vegetable oil he gets free from local restaurants. Roberson stores the waste vegetable oil that restaurants are finished using in large, blue plastic barrels in his garage. He filters out the particles and water in the oil using a commercial pump system but says the same results can be achieved by pouring the oil through a $10 filtering sock.
The filtered fry oil he uses is not the same thing as biodiesel fuel, which requires chemical processing. Once the oil is filtered, he transfers it to an auxiliary tank sitting in the bed of his truck. The tank is about the same size and shape as a toolbox.
Roberson starts his truck using normal petroleum diesel stored in the stock tank. This warms up the engine and gets the filtered waste vegetable oil hot enough to spray evenly through the fuel injectors.
Roberson said heat is the key to making the system run smoothly. At room temperature or lower, vegetable oil is too thick to work in a diesel engine. But at about 160 degrees, vegetable oil is about as thin as diesel fuel.
By keeping an eye on the gauges in the cab of his truck, he knows when the system is hot enough to start running on waste vegetable oil.
The clattering engine quiets down when he switches over. The diesel smell of an airport tarmac is replaced by that of a greasy spoon restaurant. Using this system, Roberson estimated he can squeeze about 40 miles per gallon out of his petroleum diesel supply. He said the fuel efficiency isn't an issue.
"What do you care?" he said. "It's free!"
Roberson warned that running a vehicle using waste vegetable oil can affect the longevity of a diesel engine - especially when not done properly.
"If you do not heat it enough, it decreases," he said. "If you do it right, it will increase longevity because it is a better lubricant (than diesel fuel)."
He said he hasn't noticed any difference in performance either. Roberson, who started working as a mechanic in 1973, did his first vegetable oil conversion in 2006 and said he's done more than a dozen conversions since then.
While he is passionate about the systems that he studies and installs, he doesn't hesitate to talk about the drawbacks.
"It's impractical for two- to three-mile drives," he said. "If your daily commute is more than 10 miles one way, it's viable."
He also acknowledged that the viability of a waste vegetable oil system is mainly economic and doesn't have a large impact on improving the environment. In order for waste vegetable oil conversions to have any significant environmental impact, they would have to be used on a significant scale, he said. Roberson doesn't think that will happen.
"I think it will always be small-scale," he said. "It's inconvenient. It's sticky. It's messy."
He also cautioned that converting a diesel engine to run on vegetable oil can void a manufacturer's warranty.
Erik Tedhams, service manager at German Auto in Phoenix, agreed. Tedhams said the biggest problem he sees in converted vehicles - besides the crude, makeshift systems installed by amateurs - is clogged filters.
"If you really love your car, I wouldn't do it," he said.
Another person opposed to waste vegetable oil conversions is Patrick Neel, service manager at A-1 Restaurant Services. He said people taking vegetable oil from restaurants is hurting his business "tremendously."
Neel used to charge about $20 per month for the oil collection service he provides to client restaurants. Now, with competition from people looking for a free fuel supply for their vehicles, he has to take the oil away free as well.
"I'm not afraid of competition," he said. "There's just no regulation. I just want them to do it legally."