Valero Energy Corp., which produces about 10% of California's gasoline, said it will buy Newhall-based Huntway Refining Co. for about $78 million to gain refineries in Benicia and Wilmington. Huntway stockholders will get $1.90 a share, the companies said. Huntway shares rose 13 cents to close at $1.83 on the New York Stock Exchange. San Antonio-based Valero will retire Huntway's outstanding debt and cash out outstanding options, the companies said, without giving details. Valero shares rose 30 cents to close at $35.85 on the NYSE.