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Winter’s cold and diesel fuel don’t mix. When temperatures drop, performance of standard #2 diesel fuel suffers, making engines operate poorly or not start at all.
Cold weather diesel engine problems are caused by fuel gelling or water contamination. Fuel gelling occurs when prolonged freezing temperatures create wax crystals in #2 diesel fuel, which clog fuel filters and fuel lines.
“These issues with winter diesel fuel can lead to downtime,” says Charlie Carter, an energy product quality and additives manager at CHS. “It’s important to take precautions to prevent these issues from occurring, especially in cold weather conditions.”
Winter diesel 101
Two key indicators determine operability of diesel fuel for cold weather: cloud point and cold filter plugging point (CFPP).
Cloud point is the temperature at which wax crystals become visible in a fuel sample, giving the fuel a cloudy appearance. CFPP is the lowest temperature at which fuel still flows through a specific filter.
“The cloud point is really the first indicator of cold weather operability temperatures for diesel fuel,” Carter explains. “The CFPP is a more complicated procedure, but it gives us the precise temperature at which we can keep engines running in the winter.”
Cold weather tips
To keep engines running, Carter recommends seasonal blending of diesel fuel for cold weather conditions. Combining #2 diesel fuel with a lighter diesel fuel, generally referred to as #1 or Y-grade diesel fuel and potentially a cold flow improver additive, can help engines operate efficiently as temperatures drop.
“Based on the expected temperatures in your area and diesel characteristics, you’re going to need to blend a certain amount of #1 diesel fuel and cold flow improvers to ensure diesel fuel will flow and your engine will start,” Carter says. “If you don’t, your engine won’t start until that fuel is warm enough to get back into a liquid state. This can lead to frustration and costly downtime.”
As the mercury dips, Carter notes it can be hard to know when it’s time to switch diesel fuel blends.
“Every situation is different and somewhat temperature dependent. It’s important that you work with a knowledgeable fuel supplier who has a grasp on diesel fuel characteristics and your area’s weather,” he says. Typically, “You should be blending tanks to a winter blend when temperatures are around 32 degrees Fahrenheit.”
Carter explains it’s important to blend when fuel is at least 10 degrees above the cloud point of the fuel for effective mixing. Once a tank is blended with #1 diesel fuel and a cold flow improver additive, equipment operators can gradually increase that percentage of #1 diesel fuel as temperatures drop to achieve the desired performance and cold weather operability.
Best fuel blend
When deciding what winter diesel fuel blend is best for your operation, Carter recommends basing it off typical temperature in which equipment will be operating.
“If your equipment needs to run in harsh climates, invest in a diesel fuel blend that’s going to meet those needs,” Carter advises. “It’s best to discuss specific needs with your fuel supplier because they will be able to deliver high-quality Cenex® premium diesel fuels at the correct blends for optimal performance and peace of mind.”
