SAN FRANCISCO, Aug 12 (Reuters) - Los Angeles wholesale gasoline differentials for August delivery declined on Wednesday for the first time this week as refineries stopped buying in the market, traders said.
August-delivery CARBOB gasoline differentials last traded at 90 cents a gallon over September RBOB futures on the New York Mercantile Exchange, down 15 cents from Tuesday's price in light volumes.
More activity was seen for September-delivery CARBOB gasoline, which traded multiple times and steadily declined from a high of 58 cents in the morning until finally finishing 41 cents a gallon over October RBOB futures, traders said.
Government data showing that gasoline stocks for the region rose by 300,000 barrels to 27.1 million barrels also weighed on L.A. differentials on Wednesday, traders said. Regional stockpiles of distillates also gained 600,000 barrels to 13.8 million barrels, according to the Energy Information Administration, which put downward pressure on diesel differentials.
CARBOB gasoline is mandated by the California Air Resources Board (CARB) for use in the state. It meets more stringent anti-pollution standards than gasoline in other parts of the country as required by the U.S. Environmental Protection Agency. CARBOB is made to blend with ethanol.
August-delivery EPA gasoline in the Portland, Oregon, market was seen 26 cents a gallon over NYMEX RBOB, up 4 cents from Tuesday's price.
As with gasoline, a California-specific ultra low sulfur diesel (ULSD) is also required by CARB with a more stringent formula than EPA diesel standards.
August-delivery L.A. CARB diesel fell 1.5 cents to end a 3 cent discount to September ULSD futures, while San Francisco CARB diesel was a 4.5-premium over futures, unchanged from Tuesday's price, traders said.
Portland EPA diesel was slipped a penny to finish 1 cent under September NYMEX ULDS, traders said.
August-delivery L.A. jet fuel traded several times for 2 cents under September NYMEX ULSD and was last seen bid 1.75 cents under and offered 1.25 cents under futures. (Reporting by Rory Carroll; Editing by Ken Wills)