May 27 (Reuters) - Physically traded U.S. crude grades broadly firmed on Wednesday, dealers said, after data from the American Petroleum Institute showed another weekly decline in crude stocks.

U.S. crude stocks fell for the sixth straight week last week, market sources said, citing American Petroleum Institute figures on Wednesday, while gasoline stocks also declined.

Separately, President Donald Trump on Wednesday dismissed a report that Iran and Oman would manage shipping through the Strait of Hormuz in a sign that any easing of supplies through the Strait of Hormuz remained elusive.

On the demand side, PBF Energy's 160,000 barrel-per-day refinery in Torrance, California, experienced an unplanned flaring event, according to a community alert on Monday, with production likely impacted, a person familiar with the matter said.

U.S. oil refiners are expected to have about 180,000 barrels per day of capacity offline in the week ending May 29, increasing available refining capacity by 48,000 bpd from the previous week, research company IIR Energy said on Wednesday. Offline capacity is expected to fall to 138,000 bpd in the week ending June 5, IIR said

Official U.S. oil stock data from the Energy Information Administration is due on Thursday at 10:30 a.m. EDT.

• Light Louisiana Sweet WTC-LLS for July delivery firmed to a midpoint of a $2.20 premium and was seen bid and offered between a $2.05 and $2.35 a barrel premium to U.S. crude futures CLc1 ​

• Mars Sour WTC-MRS rose $2.25 to settle at a midpoint of a 75-cent premium and was seen bid and offered between a 55-cent and 95-cent a barrel premium to U.S. crude futures CLc1 ​

• WTI Midland WTC-WTM firmed 5 cents to a midpoint of a $1.15 premium and was seen bid and offered between a $1.30 and $1.70 a barrel premium to U.S. crude futures CLc1 ​

• West Texas Sour WTC-WTS eased 5 cents to a midpoint of a $2.45 discount and was seen bid and offered between a $2.55 and $2.35 a barrel discount to U.S. crude futures CLc1 ​

• WTI at East Houston WTC-MEH, also known as MEH, traded between a $1.30 and $1.70 a barrel premium to U.S. crude futures CLc1

• ICE Brent July futures LCOc1 fell $5.29 to settle at $94.29 a barrel on Wednesday​.

• WTI July crude CLc1 futures fell $5.21 to settle at $88.68 a barrel on Wednesday​.

• The Brent/WTI spread WTCLc1-LCOc1 narrowed 14 cents to last trade at minus $5.55, after hitting a high of minus $5.46 and a low of minus $6.56.