Unlike any other fuel for modern engines, biodiesel can be made at home without investing heavily in special equipment.

Biodiesel is an alternative fuel used in diesel engines. Biodiesel, in its pure form, is not made from petroleum; instead, all or part of it is derived from plant oils or animal fats. In the United States, most commercial biodiesel is made from soybean oil, while in Europe, rapeseed (canola) oil is more commonly used. Biodiesel can be made from virgin oil, or from used cooking oil recycled from restaurants and food processing operations.

As a motor fuel, biodiesel has numerous advantages:

  • Biodiesel is a renewable fuel; to make more, we just grow more of the crop needed
  • Biodiesel can be produced domestically, displacing imported petroleum
  • Biodiesel reduces the amount of pollution emitted from diesel engines.

> Learn more about environmental issues related to biodiesel

Biodiesel should not be confused with straight vegetable oil, which is untreated oil that some people use as fuel in their modified diesel cars. Biodiesel is a more standardized product that can be used in most diesel engines without any modifications. In the United States, commercial biodiesel is defined by ASTM D6751 specifications, which outline specific properties of the fuel, such as viscosity and sulfur content. Rules like the ASTM standard ensure that certified biodiesel burns properly in modern diesel engines. But like conventional diesel fuel, biodiesel can only be used in diesel engines; today’s hybrids with their spark-ignition, gasoline engines cannot burn biodiesel.

Biodiesel can be used in its pure form, which is called B100 (100 percent biodiesel), or can be blended in any proportion with conventional diesel fuel. Common blends include B20 (20 percent biodiesel and 80 percent conventional diesel), and B5 (5 percent biodiesel and 95 percent conventional diesel). According to the Department of Energy, 431 fueling stations in the United States offer commercial biodiesel, although many of these locations sell only low-level blends.


So now you’re ready to sell the family jalopy and buy a VW diesel. But how do you make the biodiesel transition? And what’s it going to cost?

  • Expense: Commercial biodiesel tends to be more expensive than conventional diesel. In the spring of 2006, the average national price of a gallon of diesel fuel was $2.56, while B100 cost $3.23 (according to the U.S. Department of Energy). The price of biodiesel (including the tax incentives it receives) is getting closer to the price of conventional diesel and, in some cases, is cheaper. But this is not the case everywhere, as indicated by the DOE’s data.
  • Convenience: Finding biodiesel can be difficult. While conventional diesel is sold at roughly 3,000 retail locations in California, for example, biodiesel is offered in just 37 sites. If you live close to one of those sites, then you’re in business. Otherwise, it’s a challenge.

The inconvenience may not be such a big issue—if you’re comfortable with switching back and forth from petroleum diesel and biodiesel. If you normally run B20, but go on a trip and can only find standard diesel, fill ‘er right up. It doesn’t matter how much of either fuel is left in your tank. Splash blending is not a problem.

Do It Yourself OPEC

For many biodiesel users, the issues of pump price and location are irrelevant since these users make their biodiesel rather than buy it.

Unlike any other fuel for modern engines, biodiesel can be made at home without investing heavily in special equipment or earning a degree in chemistry. Many who make their own biodiesel use waste cooking oil as the base fuel, and restaurants are often happy to provide it to them free of charge. Other components for the reaction must be purchased, and time is required to master the production process. Once a user is experienced in making biodiesel, the per-gallon cost can be extremely low. Perhaps even more satisfying than the low cost is the knowledge that using biodiesel puts nothing in the coffers of major oil companies or major oil-producing nations and, in many cases, reuses oil that would otherwise be discarded.

Interestingly, biodiesel users note that exhaust fumes from their engines often reflect the origin of their waste cooking oil—anything from donuts to wontons.

Greasing the Wheels of Progress

Many biodiesel proponents also claim that using biodiesel can lead to less wear on engines and greater engine life. Studies confirm that blends that contain small amounts of biodiesel (up to 5 percent) have greater lubricity: they more effectively lubricate components of the fuel system, such as injectors and fuel pumps. Particularly when added to ultra-low-sulfur diesel fuel, biodiesel can play an important role in maintaining lubricity and extending the life of engine components. For this reason, most manufacturers of diesel engines in the United States approve biodiesel blends up to B5 for use in their vehicles. However, manufacturers like Volkswagen have not approved blends with higher amounts of biodiesel, nor have they blessed use of B100 in their diesel vehicles. Until they do, use of biodiesel blends above B5 in a VW engine can void the manufacturer’s warranty.

Ultimately, the decision to use B100 and other biodiesel blends is a personal choice. If you have a diesel vehicle, like the idea of making your own fuel (or live close to a biodiesel source), and are concerned about global warming, biodiesel is a good choice.