Oil’s surge to the highest level of the year may be short-lived as the highest supply in 85 years cushions against a drop in production.

West Texas Intermediate crude jumped 5.8 percent Wednesday after the Energy Information Administration said inventories rose at the slowest pace since January. Stockpiles have increased for 14 weeks to the highest level since 1930.

Prices rebounded 18 percent this month a record decline in rigs seeking oil boosted boosted speculation that production will soon slow and as refineries used more crude after seasonal maintenance. OPEC increased output by the most in four years even as U.S. shale output is poised to fall. These mixed signs are likely to whipsaw prices amid increased volatility, according to oil historian and economist Daniel Yergin.

“I have a really hard time thinking that we’ve reached a turning point,” said Bill O’Grady, chief market strategist at Confluence Investment Management in St. Louis, which oversees $3.4 billion. “You still have 480 plus million barrels of oil. I don’t think you’ll get a decline in stockpiles soon.”

WTI for May delivery increased $3.10 to close at $56.39 a barrel on the New York Mercantile Exchange Wednesday. It’s the highest settlement since Dec. 23. Brent for May settlement climbed $1.89 to end the session at $60.32 a barrel on the London-based ICE Futures Europe exchange, the highest close for a front-month contract since March 5.

U.S. crude supplies climbed 1.29 million barrels to 483.7 million last week. Monthly data going back to 1920 show stockpiles haven’t been this high since 1930. The EIA estimates U.S. production will slip in the middle of 2015 before recovering at the end of the year.

Cushing Storage

Inventories at Cushing, Oklahoma, the delivery point for WTI traded in New York, climbed 1.29 million barrels to a record 61.5 million. The hub has a working capacity of 70.8 million, according to the EIA.

WTI could see a “potentially large pullback that could take prices back to the low $40 range as Cushing storage nears its maximum working capacity,” Vikas Dwivedi, an analyst in Houston at Macquarie Capital Inc., said in a report Tuesday.

Crude production fell 20,000 barrels a day to 9.38 million last week, according preliminary estimates by the EIA. Still, output will rise to average 9.23 million barrels a day this year, the highest since 1972, according to the EIA, and then to 9.31 million in 2016.