U.S. crude oil inventories surged last week to another record high, while gasoline stocks went the other direction, posting their largest one-week drop in nearly six years, the Energy Information Administration said on Wednesday.
Crude inventories rose 8.2 million barrels in the week to March 3, compared with analysts' expectations for a 2 million-barrel build. Most of that - 4.6 million barrels - came from an unexpectedly large surge in stocks on the west coast.
The ninth weekly crude build boosted total stockpiles, excluding the nation's strategic petroleum reserves, to a fresh record of 528.4 million barrels.
Crude stocks at the Cushing, Oklahoma, delivery hub for U.S. crude futures also rose 867,000 barrels, the EIA said.
On the other side of the refining equation, gasoline posted its biggest weekly inventory drawdown since April 2011, with a 6.6 million-barrel drop, owing to strong nationwide demand and reduced refining output on the U.S. East Coast.
Analysts in a Reuters poll had forecast a 1.4 million-barrel drop in gasoline stocks.
"Crude stocks were bolstered by rebounding imports, while both gasoline and distillates draws were exacerbated by higher implied demand," said Matt Smith, director of commodity research at ClipperData.
U.S. crude imports rose last week by 385,000 barrels per day.
U.S. gasoline futures rose sharply on the news, hitting a session high of $1.7072 a gallon before backtracking to $1.6899, a 0.6 percent gain on the day, by 11:14 a.m. EST(1614 GMT).
U.S crude futures extended losses after the bigger-than-expected build, trading 92 cents lower at $52.22 a barrel.
The divergent prices for feedstock and product boosted the gasoline crack spread, an indicator of refining margins, to a one-week high at $18.91 a barrel.
Michael Korn, a broker at Sweet Futures in Princeton, New Jersey, said if crude inventories continue to rise, it could benefit crack spreads if gasoline stocks fall as demand rises.
That would help refiners, who were hurt by weak margins last year due to oversupply, as the summer driving season approaches.
Refinery crude runs slipped by 172,000 bpd as utilization rates edged down 0.1 percentage point to 85.9 percent of total capacity, EIA data showed.
Distillate stockpiles, which include diesel and heating oil, fell by 2.7 million barrels, three times more than forecast.
(Reporting By David Gaffen; additional reporting by Scott DiSavino and Ethan Lou; Editing by Marguerita Choy)