Winter Diesel Operability: Expect the Unexpected

From an unexpected blizzard in the South to a crippling ice storm in the Midwest, or even a surprising 70°F Christmas Day in New York, winter weather always keeps fleets guessing. When it comes to winter diesel operability, fleet managers and operators must be ready to expect the unexpected.

This years, forecasts point to a colder and snowier winter across much of the Midwest and Northeast. After Winter 2024-25 brought record-breaking snowfall and dangerously low temperatures, the Farmers' Almanac is calling for another active season. The publication describes the upcoming months as an "old-fashioned winter," featuring repeating cycles of cold, snow, and brief thaws.

Wintry conditions could begin earlier than the calendar suggests, with cold air "sneaking in" across northern states by late fall. While the best chance for a White Christmas appears centered on the Northern Plains, snowfall and cold are forecast to extend well beyond the official end of winter, lingering into March and even April across the Great Lakes, New England, and the Northern Plains.

Winter Diesel Operability

Winterizing diesel fuel is a necessity in most parts of the U.S. due to the cold flow properties of ultra-low sulfur diesel. ULSD contains paraffin wax molecules that remain fully soluble at mild temperatures but crystalize and compound together to form sheets of wax as temperatures plummet.

These wax sheets then get drawn into the fuel filter, either at the fuel dispenser or in the fuel system of the engine. This wax buildup continues to compound until the filter is clogged and soluble fuel is unable to penetrate the filter. When this happens, it starves the nozzle or engine of fuel and shuts down operations.

Challenges with winter operability are compounded by the introduction of biodiesel, which is prone to premature wax fallout and gels at a higher temperature.

Emergency Preparedness

Having onsite inventory of cold flow improver, emergency reliquifier, and water dispersant additives is a simple step consumers can take toward being prepared for sudden extreme temperatures. Preparedness also requires a current knowledge of the condition inside fuel storage tanks. A fuel testing program provides the insight needed to be proactive in protecting the fuel inside the tank from the onslaught of winter.

Cold Flow Improver Additive

Using a cold flow improver (CFI) ahead of an impending cold snap can greatly improve fuel performance during an extreme winter event. Ideally administered at the time of fuel delivery, CFI additives must be properly mixed into the fuel. When properly blended, CFI additives modify the structure of the waxy molecules in fuel, preventing them from glomming together and creating filter-plugging sheets.

Increasing the treat rate of CFIs may provide additional protection. However, anything above a double treat rate generally has significantly diminishing returns.

Emergency Reliquifier

Emergency reliquifier is a fuel additive that is administered directly into a vehicle that has already experienced-or is expected to experience-the effects of fuel gelling or icing. Reliquifier dissolves congealed fuel or ice and returns it to a liquid state, inhibiting further gelling or icing. The additive is supposed to be used as a reactive measure to ensure operability in extreme conditions and is not intended for consistent preventative treatment.

Water Dispersant

Water in diesel fuel, while fostering microbial growth and corrosion, can also be detrimental to winter operability. Water quickly freezes in the fuel lines and filters, causing filter plugging, fuel starvation, and ultimately, inoperability. A water dispersant additive, properly blended into the fuel, will rid diesel of entrained water that can lead to equipment failure if left untreated.

Fuel Testing

• A comprehensive fuel testing program provides necessary insight as to the interior condition of a fuel storage tank. A testing program should include two basic types of analyses: a bottom sample test and a nozzle sample test.
• Bottom samples are drawn using a device known as a fuel thief or bacon bomb.
• Fuel samples taken from the bottom of the storage tank provide data on the extent of contaminants in fuel. A bottom sample is typically tested for water content, sediment accumulation, and microbial growth and should be tested right before winter to ensure such contaminants do not compound issues around winter operability.
• Nozzle sample tests provide data on the cold flow properties of winter fuel. Taken from the dispenser, a nozzle sample provides key operational metrics such as cloud point, cold filter plug point, and water content-all of which are critical in terms of winter operability. Nozzle samples should be drawn and tested at least once a month during winter, and more frequently if operationally practical.

A Comprehensive Solution

While winter weather continues to be notoriously unpredictable, being prepared in the short-term requires constant weather tracking. Forecasts should be monitored up to two weeks out to allow adequate time for any preventative treatments or adjustments required. As a rule of thumb, a site should winterize its fuel for protection down to the tenth percentile of historical temperatures in that region. For any temperatures beyond that, emergency blending procedures should be incorporated.

An optimal blending program that leverages actionable insights gleaned from test results combined with the cold flow benefits of winter additives can achieve significant cost savings and ensure ongoing customer operability.

Your Trusted Partner

Mansfield offers extensive coverage and has a proven track record of delivering effective solutions for businesses facing winter fueling challenges.

By working closely with Mansfield, you can benefit from our industry expertise, cutting-edge additives like ColdPro, and a commitment to delivering the solutions you need to keep your operations running smoothly during even the harshest winter conditions. With Mansfield, you can navigate the complexities of winter-fueling with confidence and peace of mind. Contact us today!