July 22 (Reuters) - Cash price differentials for Mars Sour, a key U.S. sour crude grade, strengthened slightly on Tuesday, taking a break from a free fall in price after quality issues caused the U.S. to release barrels from its emergency stockpile.
Mars Sour WTC-MRS strengthened 10 cents at a midpoint of a $1.30 discount to U.S. crude futures CLc1.
Cash prices for the grade had weakened since July 11, just after the U.S. Department of Energy said it would provide up to 1 million barrels of crude oil from the Strategic Petroleum Reserve to Exxon Mobil's XOM.N Baton Rouge refinery in Louisiana, citing an offshore supply disruption.
The startup of an offshore well caused zinc contamination in Mars crude, Chevron CVX.N said on July 11.
Mars cash differentials weakened to a $1.40 discount on Monday, the weakest since October 2024.
Other grades on Tuesday were broadly little changed, as the front-month U.S. West Texas Intermediate crude futures contract CLc1 expired. Its expiration will kick off the relatively volatile three-day roll trading period on Wednesday, during which traders square positions.
* Light Louisiana Sweet WTC-LLS for August delivery was little changed at a midpoint of a $2.60 premium and was seen bid and offered between a $2.40 and $2.80 a barrel premium to U.S. crude futures CLc1
* Mars Sour WTC-MRS strengthened 10 cents at a midpoint of a $1.30 discount and was seen bid and offered between a $1.40 and $1.20 a barrel discount to U.S. crude futures CLc1
* WTI Midland WTC-WTM was little changed at a midpoint of a 10-cent premium and was seen bid and offered between parity and 20-cent a barrel premium to U.S. crude futures CLc1
* West Texas Sour WTC-WTS was little changed at a midpoint of a 70-cent discount and was seen bid and offered between an 80-cent and 60-cent a barrel discount to U.S. crude futures CLc1
* WTI at East Houston WTC-MEH, also known as MEH, traded between a 20-cent and 40-cent a barrel premium to U.S. crude futures CLc1
* ICE Brent September futures LCOc1 fell 62 cents to settle at $68.59 a barrel
* WTI August crude CLc1 futures fell 99 cents to settle at $66.21 a barrel
* The Brent/WTI spread WTCLc1-LCOc1 widened slightly to last trade at minus $3.26, after hitting a high of minus $3.23 and a low of minus $3.31
(Reporting by Stephanie Kelly in New YorkEditing by Matthew Lewis)
((Stephanie.Kelly@tr.com))