ForConstructionPros.com

The percentage of biodiesel in the blend determines how the fuel will react. "Getting up to 20% or 50%, it is going to be a little easier to notice the differences," says Borgman. But blends at lower concentrations, such as 2% to 5%, are not as much of a problem. "If you have in-spec B2 and B5 blends, then any of the normal additives you would use for cold flow improvement are going to work for you, and you should not see a difference."

However, not everyone is ready to recommend biodiesel blends for use in cold climates. Given the recent switch to ultra-low-sulfur diesel fuel (ULSD) for the on-highway market, Stearns advises a more cautious approach. "I recommend you try to limit biodiesel use in colder climates. That just throws another variable in, especially right now with the transition to ULSD," he states. "ULSD has a higher cloud point and needs more additization. [It requires] blending with ULS kerosene or with No. 1 diesel - which are not very available at the moment. Then you throw biodiesel on top of it, which has a much higher cloud point itself."

Concerns about cleansing
Equipment age also has a lot to do with biodiesel compatibility. "B100, as well as blends of increasing biodiesel content, can act as a cleansing agent to rubber components on engines older than 1994, breaking them down over time," says Pearson.

Hall agrees, adding, "The solvent nature of biofuels is definitely going to have a higher impact on some of the older materials we used to use." This is less of an issue with more current machines. "We started using more plastic types of seals in the late 1980s and early 1990s, moving away from natural rubber in a lot of our applications."

In 1993 to 1994, seal materials switched from rubber to current materials in response to lower sulfur diesel fuels, Stearns explains. "Since 2000, all of the Caterpillar product has been using Viton seals," he notes. This eliminates compatibility concerns. "As people are switching over older engines, they should watch for seal leakage or degradation."