It’s an eco-driver’s dream: Run your car on vegetable oil. Restaurants happily give you their old cooking oil for free, you put it in your tank, and never have to pay for gas again.

Reality check:  It is possible to use cooking oil to run your car, if 1) you have a diesel engine, 2) you regularly drive long distances, 3) you shell out for a costly engine conversion kit, and 4) you properly filter the oil.  It doesn’t come that easy, but still, what rewards for the environment and your budget you’ll reap by weaning yourself from nonrenewable fossil fuels!

Here’s the skinny:

Driving on straight vegetable oil, or SVO, requires a diesel engine to which a conversion kit is installed. Car manufacturers that make models with diesel engines include Mercedes, Volkswagen, Dodge, Ford, Chevrolet, Jeep Liberty, and Isuzu. Conversion kits for diesel engines have to be installed independently—car manufacturers don’t make SVO-ready models—and are available at Frybrid and Greasecar. Converting your diesel engine to run on SVO will cost you about $2,000 for parts and labor.

It’s important to note that regular gasoline engines CANNOT be converted to run on SVO. You have to start out with a diesel engine.

SVO engines aren’t cost effective unless you drive long distances on a regular basis. Converted engines have to run on diesel for several minutes to heat up the fuel line and the SVO, and the fuel lines have to be purged in the last few minutes of every drive. According to Greasecar’s manual, driving short distances doesn’t leave enough time for the SVO to heat up, so unless you make long commutes, you’ll just be running on diesel.

Many restaurants may be happy to give you their used cooking oil because otherwise they have to pay for a disposal service. That said, some fry joints are starting to sell this newly hot commodity, which is also falling prey to biodiesel pirates. If you can’t convince the local Chinese restaurant to give you their egg roll oil, check out Fill Up for Free or Journey to Forever, online forums with links to free oil resources and chatrooms for exchanging information with fellow “greasers.”

Once you get your hands on the goods, you’ll have to filter out the water, food particles, and hydrogenated oil. You need to test it for quality using chemicals like lye and rubbing alcohol, and then filter it with special equipment like this ready-made still from Frybrid. Or, you can get clean, ready-to-drive vegetable oil at Sam’s Club and Costco, but it will only be a few cents cheaper than buying diesel at the pump.

A warning about SVO: it’s not exactly legal on public roads under the Clean Air Act because the engine kits and SVO itself haven’t received Environmental Protection Agency approval. Technically, you could get fined, but so far the EPA seems uninterested in the SVO cars currently on the road.

But now some good news: SVO is 100% carbon neutral because you’re burning the same carbon dioxide that was absorbed by the plant when it was alive. It also emits no sulfur oxide, and if you like the smell of French fries, you’re in luck!  So eco-drivers rejoice: it’s significantly better for the environment to convert your diesel engine to a two tank diesel-SVO engine, which was the whole point to begin with.

Story by Rachel Brown. This article originally appeared in Plenty in September 2008.

Copyright Environ Press 2008