Diesel fuel is more efficient than gasoline because it contains 10 percent more energy per gallon than gasoline. But there are a few kinds of diesel fuel. Just as gasoline is rated by its octane, diesel fuel is rated by its cetane, which indicates how easy it is to ignite and how fast it burns.
Diesel fuel is safer than gasoline because its vapors don’t explode or ignite as easily as gasoline vapors.
When the exhaust from conventional diesel fuel was found to cause cancer, clean diesel engines were developed. Although thousands of conventional diesel fuel-burning vehicles are still on the road, public pressure and environmental organizations have prodded individual states and the federal government to enact legislation and fund replacement programs to take them out of use as quickly as possible.
Standard diesel fuel
Standard diesel fuel (sometimes called diesel oil) comes in two grades: Diesel #1 (or 1-D) and Diesel #2 (or 2-D). The higher the cetane number, the more volatile the fuel. Most diesel vehicles use fuel with a rating of 40 to 55. You won’t have to worry about which type to use because all diesel automakers specify Diesel #2 for normal driving conditions. Truckers use Diesel #2 to carry heavy loads for long distances at sustained speeds because it’s less volatile than Diesel #1 and provides greater fuel economy.Diesel fuel also is measured by its viscosity. Like any oil, diesel fuel gets thicker and cloudier at lower temperatures. Under extreme conditions, it can become a gel and refuse to flow at all. Diesel #1 flows more easily than Diesel #2, so it’s more efficient at lower temperatures. The two types of oil can be blended, and most service stations offer diesel fuel blended for local weather conditions.
If you plan to drive in very cold weather, choose diesel fuel rated at least 10 degrees lower than the coldest temperatures you expect to encounter. Consult your owner’s manual for specifics.
Because emissions from conventional diesel fuel have been found to be extremely toxic to humans and other living things, until safer forms of this fuel are developed, be careful not to inhale the fumes while pumping it into your fuel tank. (The same goes for gasoline!)
Biodiesel fuels
Biodiesel fuels derived from agricultural materials have the potential to provide a clean-burning alternative to dwindling sources of petroleum.Rudolph Diesel’s first engine was designed to run on peanut oil, and Henry Ford envisioned plant-based fuel as the primary fuel for transportation and partnered with Standard Oil to develop biofuel production and distribution. However, currently the only type of biodiesel fuel that can be used in vehicles in the United States and Canada without violating manufacturer’s warranties is B5, a blend of 5 percent biodiesel and 95 percent regular diesel. Most diesel engines run just fine on blends of up to 30 percent biodiesel.
