Jan 24 (Reuters) - U.S. crude oil grades eased on Friday, the last day of the cash roll period that traders use to adjust their slates, dealers said.

Traders use the three-day roll period following the expiry of the WTI contract to manage exposure and square their positions, resulting in more volatile trading.

Prices to roll U.S. crude oil positions from February to March traded at 35 cents a barrel, dealers said.

U.S. energy firms this week cut the number of oil rigs, an indicator of future output, by six to 472 this week, energy services firm Baker Hughes BKR.O said in its closely followed report on Friday.

In refining news, TotalEnergies TTEF.PA shut the small crude distillation unit (CDU) because of the outage of a coker at its 238,000-barrel-per-day (bpd) Port Arthur, Texas, refinery, people familiar with plant operations said on Friday.

CVR Energy CVI.N said on Friday its 132,000 barrels-per-day refinery in Coffeyville, Kansas, has begun planned turnaround work following a fireat the plant's naphtha hydrotreater on Tuesday.

U.S. oil refiners are expected to have about 1.16 million barrels per day (bpd) of capacity offline in the week ending Jan. 24, decreasing available refining capacity by 91,000 bpd, research company IIR Energy said on Friday.

* Light Louisiana Sweet WTC-LLS for March delivery eased 15 cents to a midpoint of a $1.70 premium and was seen bid and offered between a $1.50 and $1.90 a barrel premium to U.S. crude futures CLc1

* Mars Sour WTC-MRS eased 10 cents to a midpoint of a 30-cent discount and was seen bid and offered between discount of 60 cents and parity to U.S. crude futures CLc1

* WTI Midland WTC-WTM eased 20 cents to a midpoint of a $1.05 premium and was seen bid and offered between a 80-cent and $1.30 a barrel premium to U.S. crude futures CLc1

* West Texas Sour WTC-WTS firmed 35 cents at a midpoint of a parity and was seen bid and offered between a discount of 45 cents and 45-cent a barrel premium to U.S. crude futures CLc1

* WTI at East Houston WTC-MEH, also known as MEH, traded between a $1.00 and $1.40 a barrel premium to U.S. crude futures CLc1

* ICE Brent March futures LCOc1 rose 21 cents to settle at $78.5 a barrel on Friday.

* WTI March crude CLc1 futures rose 4 cents to settle at $74.66 a barrel on Friday.

* The Brent/WTI spread WTCLc1-LCOc1 widened 18 cents to last trade at minus $3.85, after hitting a high of minus $3.59 and a low of minus $3.93.

(Reporting by Arathy Somasekhar in Houston; Editing by David Gregorio)

((Arathy.s@tr.com))