Wisconsin's Diesel Fuel Change: When And Why?

Diesel fuel changes in Wisconsin typically occur twice a year, with a transition from winter to summer blends and vice versa. In April, the sale of winter diesel fuel, which has a higher percentage of #1 diesel for colder temperatures, ceases, and stations begin to offer summer diesel, which may include biodiesel. This process reverses in October, when summer diesel sales end, and the winter blend gradually returns. The specific dates for these transitions can vary slightly from year to year and by region within the state. Additionally, global events, crude oil prices, and seasonal demand can influence diesel fuel prices in Wisconsin.

Diesel fuel change dates: April 1st and October 1st

In Wisconsin, diesel fuel change dates are typically April 1st and October 1st. These dates mark the transition between winter and summer diesel fuel blends, ensuring that the fuel is optimised for the respective seasonal temperature ranges.

April 1st: Transition to Summer Blend

On April 1st, Wisconsin gas stations generally stop delivering blended fuel, which contains a mixture of biodiesel and #1 diesel. This date signifies the switch to the summer diesel fuel blend, which is designed to perform efficiently during the warmer months. The summer blend has a lower viscosity and better combustion properties, making it suitable for the higher temperatures and changing engine demands of the summer season.

October 1st: Transition to Winter Blend

Conversely, on October 1st, the transition begins back to the winter diesel fuel blend. This blend contains a higher percentage of #1 diesel, which has improved low-temperature flow characteristics. As temperatures start to drop, the winter blend is formulated to prevent issues like fuel gelling and ensure optimal engine performance during the colder months.

The primary reason for having distinct summer and winter diesel fuel blends is to account for temperature variations. Diesel fuel can thicken and gel in cold weather, leading to engine performance issues and even damage. By adjusting the composition of the fuel, fuel suppliers ensure that vehicles and equipment can operate reliably and efficiently throughout the year.

Staying Informed about Fuel Changes

While April 1st and October 1st are the typical dates for diesel fuel changes in Wisconsin, it is always a good practice to stay informed. Fuel change dates can vary slightly from year to year, and staying up-to-date ensures that you can take advantage of the optimal fuel blend for your vehicle or equipment at any given time.

Winter diesel is suitable for year-round use

In Wisconsin, the switch from winter to summer diesel fuel typically happens on April 1st. This is when gas stations stop delivering the blended fuel. The winter blend is available again from October 1st.

Winter diesel fuel is enhanced to prevent it from gelling in cold weather conditions. This is achieved by treating the fuel with additives that change its low-temperature characteristics. Diesel fuel is prone to waxing or gelling in cold weather, which refers to the solidification of diesel oil into a partially crystalline state. The presence of solidified waxes thickens the oil and clogs fuel filters and injectors in engines, causing the engine to stop running.

The cold filter plugging point (CFPP) is a standardized test that indicates the rate at which diesel fuel will flow through a standardized filtration device over a specified length of time when cooled under certain conditions. Winter diesel has a CFPP of -12°C max, while summer diesel has a CFPP of -4°C max.

While summer-grade diesel is only certified for use during the summer months, winter diesel can be used all year round. It is more resistant to cold temperatures and can prevent operational problems such as difficulty starting and stopping machinery, vehicle and equipment failure, and fuel starvation due to blocked filters.

However, using winter diesel all year round may not be cost-effective. Refining crude oil produces less winter-grade diesel than summer-grade diesel, which could lead to availability issues. Additionally, the energy content of fossil winter-grade fuel is lower than that of summer-grade fuel.

Diesel prices in Wisconsin: $3.33

As of January 2025, diesel prices in Wisconsin are sitting at $3.33. This is a relatively standard price, with anything below $3.18 considered a good price for diesel in the state.

Diesel prices in Wisconsin, as in the rest of the United States, fluctuate depending on the time of year. In Wisconsin, the winter blend of diesel is typically delivered to stations from October 1st, with the summer blend usually arriving on April 1st. The winter blend is stronger to account for the colder weather, with the number of BTUs per gallon slightly lower than in the summer blend.

Some people choose to treat their diesel with additives all year round to prevent gelling in cold weather, rather than switching between blends. This is a personal preference, and some sources suggest that using winter diesel in warmer weather will not cause any issues.

It is worth noting that the changeover from summer to winter diesel in the fall is generally considered more important than the switch back to summer diesel in spring. This is because the properties of the winter blend are designed to prevent issues caused by colder temperatures.

Factors influencing diesel prices: global conflict, crude oil prices, weather, demand

In Wisconsin, the switch from winter to summer diesel fuel typically happens on April 1st, with the former being delivered to stations until then. The transition back to winter blend starts on October 1st.

Now, let's delve into the factors influencing diesel prices, including global conflict, crude oil prices, weather, and demand:

Global Conflict and Political Stability

Geopolitical events and conflicts in oil-producing regions can potentially interrupt supply and influence prices. For instance, tensions in the Middle East often lead to spikes in crude oil prices. The Organization of the Petroleum Exporting Countries (OPEC) also significantly impacts the oil market by managing oil production and prices.

Crude Oil Prices and Production

The cost of crude oil is the most significant component in diesel fuel pricing. When crude oil prices rise, so do diesel prices, as refining crude oil into diesel becomes more expensive. Production costs depend on the extraction process and the location of the oil field. For example, offshore drilling is generally costlier than drilling on land.

Global demand, influenced by economic growth, also plays a crucial role. A booming economy increases oil demand, driving up prices. Conversely, a slowing economy reduces demand and prices.

Weather

Weather patterns, particularly winter weather, can influence diesel prices. Cold winters lead to higher demand for heating oil, which is a distillate of crude oil. The Northeastern US is the world's largest consumer of heating oil, so cold weather in this region can impact diesel prices.

Demand

Demand is a critical factor in diesel pricing. High demand leads to increased prices due to competition for limited supply. Conversely, low demand results in decreased prices as suppliers are willing to sell at lower prices to move the product.

Seasonal changes also affect demand, with diesel demand typically increasing during the summer travel months. Additionally, economic downturns can cause demand to decrease as people cut back on spending.

Diesel prices in Wisconsin compared to other states

In Wisconsin, the switch from winter to summer diesel fuel typically happens on April 1st, when stations stop delivering blended fuel. On October 1st, the switch back to winter blend fuel begins, with the percentage of #1 fuel increasing until January and decreasing again in February as temperatures become milder.

As of January 2, 2025, the average diesel price in Wisconsin was $2.880 per gallon, which is lower than the national average of $3.067. While a direct comparison with other states is not possible with the current data, Wisconsin's diesel prices are likely influenced by various factors, including local taxes, transportation costs, and competition among fuel retailers.

Diesel prices can vary significantly across different states in the US due to differences in taxation, fuel production, and distribution networks. Some states may have higher diesel prices due to higher fuel taxes, while others may benefit from a more competitive market with lower prices. Additionally, the proximity to refineries and the cost of transportation can impact the price at the pump.

It is worth noting that diesel prices can fluctuate daily, and the prices mentioned earlier may not be reflective of the current market. Diesel prices are influenced by global oil prices, supply and demand dynamics, and seasonal variations. As such, it is essential to monitor reliable sources for the most up-to-date information on diesel prices in Wisconsin and other states.

To conclude, while a direct comparison of diesel prices between Wisconsin and other states is challenging due to the dynamic nature of fuel prices, Wisconsin's prices appear competitive, and the state's transition between winter and summer diesel blends follows a similar pattern to other regions, with adjustments made according to temperature changes.

Frequently asked questions