It’s that time of year again, cooler mornings, frosted windows, which means it’s time to winterize your stored diesel fuel. If No. 2 diesel cools during colder, overnight temperatures, it may reach “cloud point,” when wax crystals develop in the fuel. The fuel will look cloudy and crystals can plug the fuel filter, resulting in poor starts, engine hesitation, stalling and even engine damage. Use the below guidelines to winterize fuel left over from harvest.

Know When to Blend

The cloud point for No.2 diesel is approximately 14 degrees F. A good rule of thumb is to switch to a winter blend 15 degrees above cloud point. When overnight temperatures begin to dip down near 30 degrees F, it’s time to blend in No.1 diesel with additives for winter. For every 10 percent of No. 1 diesel added, the fuel cloud point will drop by 3 degrees F.

Don’t let cloud point surprise you – crystals can quickly accumulate in the fuel during a cold snap but may still run fine. Even if the fuel is blended after reaching cloud point, those crystals will remain and can clog your equipment. An engine that runs well on a chilly Friday could leave you stranded on a warm Monday. For this reason, an early-season move to winter-grade fuel is always recommended.

Factor in the Remaining Inventory

When blending fuel, don’t just pour No. 1 diesel on top of stored fuel. First gauge the remaining inventory – or the total volume of No. 2 left in the tank before you begin blending winterized fuel – and reach the proper blend before bringing in the first delivery of winterized product. If No. 1 diesel is added to the storage tank without proper blending, the winterized product can be diluted, negatively impacting the fuel quality. 

Ask Questions

When done correctly, fuel blending will improve diesel engine performance. But since it’s a scientific process that can vary based on expected regional temperatures and your specific operation, you may have a few questions along the way. Your local Cenex® dealer can help answer your questions and help you achieve the right winter blend for your equipment. Our cold weather diesel fuel, Cenex® Wintermaster®, offers operability to minus 30 degrees F.

An early switch to a winter blend diesel fuel will help keep your operation and equipment running smoothly this winter.

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