Updated April 5, 2026 — Prices updated regularly from EIA data
$3.67
Regular Unleaded (87 octane) per gallon
About Regular Unleaded in Decatur
Regular 87-octane gasoline costs $$3.67 in Decatur, Illinois as of {month} {year}. With thousands of stations competing for the regular fuel customer, this grade sees the sharpest price competition of any tier.
For vehicles designed to use Regular Unleaded, using the correct grade maintains engineered fuel economy. Upgrading from regular to premium in a regular-fuel car produces no economy improvement. Using regular in a premium-required car may reduce fuel economy slightly.
National Regular Unleaded prices average ${natPrice} per gallon. Decatur's current price of $$3.67 is {comparison} the national average. Regional refinery access and state tax differences drive most of the variation.
TOP TIER certification means the fuel exceeds EPA minimum detergency standards. Studies suggest TOP TIER fuels meaningfully reduce engine deposits vs. minimum-standard fuels. Most major brands (Shell, Chevron, BP, Costco) are TOP TIER certified.
Mixing grades is generally fine in practice — your engine's knock sensors will adjust timing accordingly. If your vehicle requires premium and you add some regular, no immediate damage occurs. Consistently running below the required octane in a performance engine is not recommended long-term.
