Tesoro Corp., the San Antonio refiner that operates Hawai'i's largest refinery, is forecasting it will process less crude oil at its Campbell Industrial Park facility during the fourth quarter than it did a year earlier.

Tesoro anticipates throughput at its Hawai'i operation will be 60,000 to 70,000 barrels a day during the October-to-December quarter, the company said yesterday on a conference call with investors and analysts.

If the projection holds, throughput would be lower than the 74,000 barrel throughput Tesoro averaged in Hawai'i during the 2007 fourth quarter. During the most recent quarter, the local refinery's throughput fell as sales of gasoline, jet fuel and other petroleum products slipped.