HOUSTON, Aug 8 (Reuters) - U.S. crude oil refiners are

trimming third-quarter production plans, company executives said

in recent earnings calls, as summer fuel demand ebbs and profit

margins remain weak.

Operators say they are budgeting more maintenance downtime

into forecasts after running at an industry average 95% of

capacity earlier this year. Those high oil processing levels led

to plentiful gasoline stocks, which benefited motorists but hurt

profits.

Matthew Blair, top refining analyst at energy firm Tudor,

Pickering, Holt & Co, said refiners are reflecting a weakened

margin environment in the third quarter with softer demand.

"The hope is if you lower supply you may get higher

margins," Blair said, noting the projected percentages of

capacity cited by Marathon Petroleum ( MPC ), Valero Energy ( VLO )

and Phillips 66.

Top U.S. refiner Marathon Petroleum ( MPC ) said it would operate

its 13 refineries at 90% of their combined crude intake capacity

of 3 million barrels per day (bpd), down from 97% of capacity

last quarter.

Valero Energy ( VLO ), the second-largest U.S. refiner, plans to

reduce its processing rate due to plant maintenance and soft

margins. The midpoint of its processing target is about 2.86

million bpd, down from 3 million bpd last quarter.

Phillips 66, which ran at a five-year high of 98% of

capacity in the second quarter, is planning to run its plants in

the low-90% of capacity range, executives said, citing a

softening in the fuels market.

"Utilization is coming down sort of across the sector," said

PBF Energy ( PBF ) CEO Matthew Lucey, whose company did not

project its third-quarter run rate. "In the summertime, again,

we'll lose some utilization," he said.

"We're optimizing our refineries in light of these market

conditions," said Greg Bram, vice president of refining services

at Valero, referring to the company's plan to reduce operating

rates.

HF Sinclair ( DINO ) expects planned plant overhauls will

reduce its combined run rate by about 7.8% at the midpoint of a

range of between 570,000 bpd and 600,000 bpd. Its network ran at

a rate of 635,000 bpd last quarter.

The U.S. government's sale of 1 million barrels of gasoline

last quarter from its Northeast supply reserve benefited

consumers but hurt refiners. Operators hope supply cuts from

maintenance will gradually improve margins this quarter.