By Abigail GerryPublished On: August 28, 2025Categories: Daily Market News & Insights, Fuel Prices

Fuel might look the same every time you fill up, but blends change throughout the year for reasons that often get overlooked. Beyond fluctuations in price and availability, seasonal changes in temperature and regulations directly affect how fuel is formulated and how well it performs in each season. These seasonal shifts can have a direct impact on how fleets operate, affecting engine efficiency and maintenance schedules.

As temperatures change throughout the year, refineries adjust blends to meet regulatory requirements and ensure reliable performance. For fleets, these seasonal fuel transitions can affect efficiency, costs, and overall reliability. Because seasonal blends are tailored for temperature extremes, using the wrong fuel at the wrong time of year can create performance issues. Understanding the differences between summer and winter fuels, and planning ahead, helps fleet managers keep operations running smoothly and maintain a strong program year-round.

Why Seasonal Fuel Blends Exist

Consider summer fuel blends and the annual price swings they bring at both the rack and the pump. Each summer, fleets and everyday drivers face the reality of higher fuel costs. Why is fuel more expensive in the summertime? While market dynamics play a part, a portion of the seasonal price increase comes from the required transition to summer fuel blends. The EPA mandates these blends to ultimately help reduce air pollution, but this shift also brings added complexity and cost to the supply chain.

Fuel volatility, emissions standards, and weather conditions all hold a spot in seasonal changes. Reid Vapor Pressure (RVP) indicates how easily gasoline evaporates under heat. In summer conditions, fuels with high volatility evaporate more quickly, releasing volatile organic compounds (VOCs) into the atmosphere. These emissions contribute to ground-level ozone and smog, which are both harmful to human health and the environment. In colder months, refiners produce winter-grade fuel with higher RVP, which allows engines to start more easily in low temperatures.

What is the Impact on Fleets?

With fluctuating pricing and sometimes fluctuating availability, the biggest impact of seasonal fuel blends falls on fleets. Seasonal fuel blends may seem like a regulatory formality, but for fleets, the effects are felt in day-to-day operations:

Fuel Efficiency: Winter blends often contain lighter components or additives to aid ignition in cold weather, but this can lower energy density, reducing miles per gallon. Summer blends, while more stable, generally provide better efficiency.
Maintenance Needs: Cold-weather diesel requires additives or blending to prevent gelling, while warmer weather increases the risk of vapor lock and demands stricter storage practices.
Operational Reliability: Using the wrong blend or failing to prepare equipment for seasonal changes can lead to sluggish starts, filter plugging, or fuel delivery issues.

For fleet managers, these impacts underline the importance of anticipating seasonal transitions, coordinating closely with suppliers, and monitoring performance data to keep operations running smoothly year-round.

Planning Ahead for Seasonal Shifts

One of the most important steps in staying ahead of seasonal fuel blend challenges is planning. While you can’t control how fuel is blended or the pricing that comes with it, you can plan ahead to ensure you have reliable access to the right fuel when you need it. Fleets can better navigate seasonal changes by:

Working with a Reliable Supplier: Coordinating with a reliable fuel provider ensures access to the correct seasonal blend at the right time.
Optimizing Maintenance Schedules: Implement preventive maintenance to confirm fuel systems, tanks, and filters are ready for changing blends.
Leveraging Data Tools: leveraging platforms like FuelNet gives visibility into usage and performance, helping fleets respond quickly to changing conditions.

Seasonal fuel changes are part of the regulatory and environmental landscape, but they don’t have to catch your fleet off guard. By understanding the differences in blends and partnering with Mansfield, fleets can minimize disruptions, manage costs, and keep vehicles performing at their best year-round. Contact us today!

This article is part of Daily Market News & Insights