The Weekly Fill-Up | May 18-22

May 18, 2026

Fuel markets are entering a more uncertain phase this week as global events begin creating ripple effects that could eventually influence diesel pricing and supply conditions across the Midwest. While Sioux Valley Coop patrons are not seeing major disruptions locally right now, several developments happening worldwide are worth watching because they directly affect the fuels that power agriculture.

The biggest story influencing markets this week is continued instability surrounding oil transportation routes in the Middle East. Ongoing tensions involving Iran and shipping activity near the Strait of Hormuz have kept global crude oil markets volatile. The Strait of Hormuz is one of the most important oil transit points in the world, moving a significant share of global crude exports every day. Concerns about reduced shipping access or disruptions in that corridor pushed crude oil prices sharply higher earlier this spring, and markets remain sensitive to any additional escalation.

Why this matters locally is because diesel fuel markets tend to react faster and more aggressively than gasoline markets when global supply uncertainty develops. Diesel inventories worldwide remain tighter than many other refined fuel products, and diesel production depends heavily on refinery output and crude quality. Analysts continue to point out that diesel supplies are structurally tighter than they were a few years ago due to refinery closures and changing production economics.

For Sioux Valley Coop patrons, this creates a situation where diesel availability remains stable for now, but price volatility could increase quickly if global conditions worsen. Mid-May is already a period of elevated agricultural demand across the Midwest as planting activity, transportation, and input movement continue at a heavy pace. When local seasonal demand overlaps with global uncertainty, diesel markets become much more sensitive to sudden changes.

Another important development this week involves renewable diesel and biofuel production. The U.S. Environmental Protection Agency’s expanded biofuel blending requirements are increasing demand for soybean oil and renewable fuel feedstocks. Refiners are now producing larger volumes of renewable diesel and biodiesel to meet federal mandates, which is changing how traditional diesel markets behave.

For South Dakota agriculture, this matters in several ways. Stronger soybean demand tied to renewable diesel production can support regional ag markets, but it also contributes to tighter competition within fuel refining systems. Some refiners are prioritizing conventional diesel production because current diesel margins remain strong globally, while others continue investing heavily in renewable fuels. That balancing act could continue influencing diesel pricing throughout the summer.

Locally, planting activity across eastern South Dakota continues driving steady diesel usage. Favorable weather windows have allowed many operations to stay active consistently, which keeps fuel demand elevated throughout the region. Unlike earlier in the spring when activity came in shorter bursts, current usage patterns are more sustained. That steady draw increases the importance of delivery scheduling and inventory management, especially during periods where market volatility is elevated globally.

Propane markets remain much calmer by comparison. National propane inventories continue sitting in a healthy position following a relatively mild winter and stable spring demand. With residential heating season now behind us, propane availability across the Midwest remains strong and pricing has stayed comparatively stable. For most Sioux Valley Coop patrons, propane is currently in a maintenance phase rather than an active concern, though maintaining adequate levels remains important for operational continuity.

The key takeaway for the week of May 18 is awareness without panic. Global oil market instability is creating additional uncertainty for diesel markets at the same time Midwest agricultural demand remains strong. Propane supply remains stable and well supplied. For Sioux Valley Coop patrons, the best approach continues to be proactive planning — maintaining communication, monitoring inventory closely, and scheduling fuel needs early while supply systems remain steady and dependable.

Sources

U.S. Energy Information Administration (EIA) – Short-Term Energy Outlook
Reuters – U.S. refiners and renewable diesel market developments
AgWeb – Diesel supply and pricing analysis for agriculture
USDA Economic Research Service – Oil Crops Outlook, May 2026
Reuters – Global diesel supply analysis