Ever hear the phrase "slow as molasses in January?" Recently, extremely cold weather in the upper Midwest and along the East Coast caused drivers of buses, trucks, and other vehicles using diesel fuel to deal with thickening fuel; fuel turning to gel. A flurry of attention occurred when it was reported that a small fleet of school buses from Bloomington, Minnesota, near Minneapolis, had been immobilized by the use of biodiesel fuel. In states which have mandates for the incorporation of biodiesel in all diesel sold, including Minnesota, fingers began to point to the alternative fuel as the culprit. What happened? Biodiesel is being touted as one alternative to fossil fuels, and we've added it to our 56 Ways to Go Green in 2009 by suggesting that you explore alternate fuel vehicles. A little investigation is in order... What caused the hitch? Let's start at the beginning. Minnesota, for example, is not only the "land of 10,000 lakes" but it is also the land of temperature extremes. Summer temperature maximums are regularly in the high 90s, and occasionally cross over into the 100s. January temperatures regularly hover in the single digits for days at a time. Minneapolis temperatures for January 13 through January 15 never made it above zero and the nighttime temperature on Friday, January 16, dropped to -24°F. Diesel fuel is susceptible to turning to gel under cold conditions; its "viscosity increases quickly as the fuel's temperature decreases, turning into a non-flowing gel at temperatures" between -2.2°F  and 5°F. There are special additives that will make it flow at temperatures as low as -20°F. (Thank you, Wikipedia.) Minnesota state law requires that virtually all diesel contain two percent biodiesel (B2). Flawed logic: The cold wave covered the whole state of Minnesota, diesel fuel sold in the state contains biodiesel, therefore biodiesel caused vehicles to stop running. Correct logic: The cold wave covered the whole state of Minnesota, wouldn’t all the diesel-fueled vehicles be affected? Turns out that the stalled fleet of school buses that made national headlines was not sidelined by biodiesel fuel:

“The problems with school buses in Minnesota had nothing to do with biodiesel,” said Bill Walsh, Communications Director for the Minnesota Department of Commerce. “An independent investigation confirmed what we believed last week – when it gets to 20 degrees below zero in the Midwest, diesel engines have trouble operating unless they are properly maintained – whether or not they are using a biodiesel blend.

A report analyzing the failure of the school buses, concluded that the filters in the buses were not plugged by biodiesel but "a substance  found in petroleum." It was a maintenance problem, not a fuel problem. Note to users of diesel (bio or not) in cold climates - good fuel with proper cold weather additives, good maintenance, and electric engine heaters will keep your vehicle running smoothly.