July 25 (Reuters) - Refiner Valero Energy posted

lower second-quarter profit on Thursday, hurt by a slump in

margins due to a tepid summer driving season and a rise in

global refining capacity.

The San Antonio, Texas-based refiner reported net income of

$880 million, or $2.71 per share, for the three months ended

June 30, below $1.94 billion, or $5.40 per share, last year.