Platts to publish a regional USGC octane cost assessment

Platts, part of S&P Global Energy, will launch a new daily assessment to reflect the value of one octane index point for US Gulf Coast conventional gasoline, effective Dec. 17, 2025.

The new assessments will standardize the octane value year-round, bringing further transparency to the US gasoline market.

The assessments will be used to estimate or adjust gasoline and gasoline blendstock prices, along with existing RVP adjustments. The octane adjustments will be published in US cents/gal per octane index point.

The new US Gulf Coast Value adjustment per one octane (83.7-91.4 AKI) reflects the resulting value of the USGC Premium CBOB pipeline (AANYX78) and USGC regular CBOB pipeline (AANYX77) differential spread divided by 7.7 octane points.

The US Gulf Coast Value adjustment per one octane (83.7-91.4 AKI) represents the value of one octane point, considering a linear octane relationship for the pre-ethanol blending range of 83.7 AKI-91.4 AKI.

For reference, the pre-ethanol octane range of 83.7-91.4 AKI is the equivalent of the post-ethanol octane range of 87-93 AKI.

The adjustment will establish a value for one point of octane between 83.7 AKI and 91.4 AKI, tracking Colonial Pipeline specifications underpinning the US Gulf Coast benchmark assessments.

Platts continues to seek wider feedback on whether separate octane values should be published for adjustments outside of that range.

The decision follows a proposal note published Oct. 17, which opened a period of feedback gathering and can be found here.

Please provide comments or feedback on this decision to americas_products@spglobal.com and pricegroup@spglobal.com.

For written comments, please provide a clear indication if comments are not intended for publication by Platts for public viewing. Platts will consider all comments received and will make comments not marked as confidential available upon request.