West Texas Intermediate oil fell for the first time in six days, widening its discount to Brent, on speculation that the closure of an Exxon Mobil Corp. (XOM) pipeline will increase U.S. inventories.

WTI slid as much as 1.3 percent as Exxon shut the Pegasus pipeline, which moves oil from Illinois to the U.S. Gulf Coast, March 29 after heavy Canadian crude leaked in Arkansas. Exxon hasn’t said when it will reopen.

The 96,000 barrel-a-day Pegasus pipeline will need to be excavated as Exxon determines what caused the breach, and Exxon is awaiting regulatory approval to begin excavation work and repairs, Alan Jeffers, a company spokesman in Irving, Texas, said yesterday.

Pegasus, a 20-inch (51-centimeter) line that runs to Nederland, Texas, from Patoka, Illinois, serves refineries near the Beaumont, Texas, area close to the Louisiana border, Jeffers said. There are four plants near Beaumont able to process about 1.4 million barrels a day of crude, according to data compiled by Bloomberg.

Oil also dropped as U.S. manufacturing expanded less than forecast in March. Futures extended their decline as the Institute for Supply Management’s factory index fell to 51.3 last month from 54.2 a the prior month earlier, the Tempe, Arizona-based group said today. The median forecast of economists surveyed was 54. Figures higher than 50 signal expansion.

WTI for May delivery slipped to $95.92 a barrel on the New York Mercantile Exchange.

Brent for May settlement dropped 21 cents to $109.81 a barrel on the London-based ICE Futures Europe exchange. The European grade’s premium to WTI widened to as much as $13.86 a barrel after settling at $12.79 on March 28, the narrowest level since June 25.