By Rebecca Richardson, Illinois Soybean Association


With crisp fall temperatures on the way, it’s time to think about preparing fuel for winter operations.

One of the myths that persists about wintertime fuel is that biodiesel can’t be used in cold weather. In truth, biodiesel blends can be used year-round everywhere ultra-low sulfur diesel (ULSD) is used.

All diesel fuels require maintenance steps to ensure proper winter performance, and biodiesel is no different.


Understanding Cold Flow

Regardless of the type of fuel, it’s important to ensure that cold flow properties are adequate for your climate at the time the fuel will be used. Two cold flow measurements are critical for standard No. 2 diesel fuel as well as for biodiesel:

  • Cloud point (CP): The temperature at which wax or gel crystals first appear in the fuel, making it appear cloudy or hazy.
  • Cold filter plugging point (CFPP): The temperature at which larger crystals form and start to plug the fuel filter. CFPP generally indicates the lowest temperature for vehicle operation. To prevent engine power loss, the CFPP needs to stay below wintertime low temperatures.

Cold flow properties for diesel fuel can vary based on crude oil source and how the fuel has been refined and blended. For biodiesel, feedstocks used for its production can affect cold flow.

Regardless of the fuel type, it’s important to winterize the fuel to withstand the expected weather. Additives help lower the CFPP and improve the flow of both diesel and biodiesel blends during below-freezing temperatures. For optimal vehicle performance it’s important to determine additive needs and apply them before fuel reaches the CP temperature.

Another way to improve cold flow is to combine No. 1 diesel, or kerosene, with diesel or biodiesel blends. However, kerosene has a lower BTU value than diesel and can reduce fuel economy. Additives are generally less expensive and perform just as well as kerosene to improve winter performance. If using No. 1 diesel, put it into the tank first, with No. 2 on top, to achieve a better blend.


Avoid Water Contamination

If you’re a fuel supplier, make sure customers’ fuel tanks are free from water or other contaminants going into winter. Water is the most common source of fuel filter plugging issues in diesel vehicles during the winter. When temperatures drop below freezing, any excess water in the tank can freeze and block the flow of fuel through the filter.

Water in the tank also leads to microbial growth. Microbial contamination has become more common since the introduction of ultra-low sulfur diesel (USLD) in 2006. Previously, the high sulfur content in diesel fuel acted as a natural antimicrobial agent.

A Bacon Bomb is an inexpensive and easy way to retrieve fuel samples to test storage tanks for water and microbial contamination. This device collects samples from the tank bottom, where free water and sediment can settle. Collected fuel samples should be clear and bright. Hazy fuel indicates water contamination.

If fuel contains water, take steps to clean and remove it, or consider a deicer to keep the water suspended and moving through the system during cold weather. Also test for microbes and treat contaminated tanks with a biocide. If contamination is severe, the tank may need to be drained and cleaned.

Because the Illinois Soybean Association recognizes the critical importance of tank maintenance for proper fuel performance, the Illinois soybean checkoff program offers free tank testing to retail locations and municipal fleets in Illinois that carry biodiesel fuel. Illinois retailers and fleet operators can contact Pete Probst at [email protected] for more information.

With proper maintenance and basic housekeeping practices, customers can expect problem-free performance from either ULSD or biodiesel blends up to B20 this winter.


Rebecca Richardson is the Biodiesel Lead for the Illinois Soybean Association ISA) is a statewide organization that strives to enable Illinois soybean producers to be the most knowledgeable and profitable soybean producers around the world. For more information: For more tips on cold-weather fuel operation, visit the National Biodiesel Board website: