HOUSTON, Feb 23 (Reuters) - Grades rose on Monday, dealers said, on the first full day of the volatile roll trading period.

Traders use the three-day roll period to adjust their crude slates, square up positions and net out exposures following the expiration of the U.S. crude futures contract.

Prices to roll U.S. crude oil futures positions from March to April traded at minus 5 cents a barrel.

U.S. oil refiners are expected to have about 1.03 million barrels per day of capacity offline in the week ending February 27, increasing available refining capacity by 118,000 bpd, research company IIR Energy said.

Offline capacity is expected to fall to 751,000 bpd in the week ending March 6, IIR said.

Coastal grades climbed as WTI's discount to Brent traded at a discount of as much as minus $5.35 a barrel during the session, its widest point since January 30.

A discount larger than $4 a barrel typically drives higher demand for barrels across the Atlantic, as traders spot an arbitrage window.

• Light Louisiana Sweet for March delivery rose 55 cents to a midpoint of a $2.80 premium and was seen bid and offered between a $2.70 and $2.90 a barrel premium to U.S. crude futures CLc1 ​

• Mars Sour rose 70 cents to a midpoint of a 90-cent premium and was seen bid and offered between an 80-cent and $1 a barrel premium to U.S. crude futures CLc1

  ​

• WTI Midland rose 25 cents to a midpoint of a 50-cent premium and was seen bid and offered between a 40-cent and 60-cent a barrel premium to U.S. crude futures CLc1

  ​

• West Texas Sour rose 30 cents to a midpoint of a $2.70 discount and was seen bid and offered between a $2.80 and $2.60 a barrel discount to U.S. crude futures CLc1 ​

• WTI at East Houston, also known as MEH, traded between a $1.15 and $1.35 a barrel premium to U.S. crude futures CLc1

  ​

• ICE Brent April futures LCOc1 fell 27 cents to settle at $71.49 a barrel

• WTI April crude CLc1 futures fell 17 cents to settle at $66.31 a barrel

• The Brent/WTI spread narrowed 11 cents to last trade at minus $5.17, after hitting a high of minus $5.13 and a low of minus $5.35

(Reporting by Georgina McCartney in Houston and Siddharth Cavale in New York; Editing by Nia Williams)

((Georgina.McCartney@tr.com))