Wholesale gasoline differentials jumped 12 cents a gallon in the Los Angeles market on Thursday morning on talk of a shut gasoline production unit at California's largest refinery, traders said.

A gasoline-producing fluidic catalytic cracking unit was shut on Wednesday at Chevron Corp's 273,000-barrels-per-day Los Angeles-area refinery in El Segundo, California, traders said. A Chevron representative was not immediately available to discuss refinery operations.

Gasoline blended to meet California's strict environmental standards traded at 30 cents a gallon over NYMEX December RBOB gasoline on Thursday morning, dealers said. It had finished on Wednesday at 18 cents over.