Crude grades were mixed on Friday, dealers said, due to volatility in the cash roll period.

Mars Sour WTC-MRS fell 35 cents at a midpoint of a 25-cent discount to U.S. crude futures. WTI Midland WTC-WTM and WTI at East Houston, also known as MEH, strengthened.

Traders and refiners use the three-day cash roll period to square their positions and adjust slates. Prices typically tend to be more volatile during the roll period.

U.S. crude’s discount to international benchmark Brent WTCLc1-LCOc1 widened to its most in more than a month to trade as low as minus $4.62 a barrel.

Meanwhile, U.S. energy firms in August cut the number of active oil rigs by 8 to 512 this week, their lowest since Feb 2022, energy services firm Baker Hughes BKR.O said in its report on Friday. RIG/U

In refining news, Marathon Petroleum Corp MPC.N said it shut down production units closest to burning naphtha storage tanks at its 596,000 barrel-per-day (bpd) Garyville, Louisiana refinery “out of an abundance of caution.”

* Light Louisiana Sweet WTC-LLS for September delivery gained 75 cents at a midpoint of a $3.50 premium and was seen bid and offered between a $3.25 and $3.75 a barrel premium to U.S. crude futures CLc1

* Mars Sour WTC-MRS fell 35 cents at a midpoint of a 25-cent discount and was seen bid and offered between discount of 50 cents and parity to U.S. crude futures CLc1

* WTI Midland WTC-WTM gained 10 cents at a midpoint of a $1.65 premium and was seen bid and offered between a $1.50 and $1.80 a barrel premium to U.S. crude futures CLc1

* West Texas Sour WTC-WTS was unchanged at a midpoint of a 25-cent premium and was seen bid and offered between parity and 50-cent a barrel premium to U.S. crude futures CLc1

* WTI at East Houston WTC-MEH, also known as MEH, traded between a $2.00 and $2.30 a barrel premium to U.S. crude futures CLc1

* ICE Brent October futures LCOc1 rose $1.12 to settle at $84.48 a barrel on Friday.

* WTI October crude CLc1 futures rose 78 cents to settle at $79.83 a barrel on Friday.

* The Brent/WTI spread WTCLc1-LCOc1 widened 31 cents to minus $4.31, after hitting a high of minus $4.25 and a low of minus $4.69.
Source: Reuters (Reporting by Arathy Somasekhar in Houston, Editing by Marguerita Choy and Will Dunham)