Tesoro Corp., which operates the largest oil refinery in Hawaii, posted a 69.7 percent rise in third-quarter earnings driven by stronger distillate margins, improved feedstock cost and the company’s improvement initiatives.

The San Antonio-based company had net income of $56 million, or 39 cents a share, compared with $33 million, or 24 cents a share, a year ago. The company earned $73 million, or 51 cents a share, for the period before one-time expenses of $17 million primarily associated with an Anacortes, Wash., refinery outage. Revenue rose 12.2 percent to $5.3 billion from $4.7 billion.

"We attribute (the improvement) to strong distillate exports, improvements in the U.S. manufacturing sector and increased port activity nationwide," Tesoro CEO Greg Goff said.

Goff said, however, that the increases are not being seen in gasoline margins.

"While gasoline demand has stabilized, high unemployment in California continues to keep gasoline demand weak."

In Hawaii, Tesoro’s refining margin rose to $5 a barrel from $1.05 a barrel in the year-earlier period. The refining margin is the spread between the cost of crude oil and price of refined products.

The yield, or the total number of barrels of refined products of gas, jet fuel, diesel fuel and heavy oils, decreased to 54,000 barrels a day from 67,000 barrels a day a year earlier. The total throughput in Hawaii fell to 53,000 barrels a day from 66,000 barrels a day.