Oil prices slipped for the fourth consecutive session in New York, under pressure from mediocre demand in the United States, the world's largest energy consumer.
New York's main contract, light sweet crude for delivery in May, fell 58 cents to 84.34 dollars a barrel after rallying above 85 dollars earlier in the day.
London's Brent North Sea crude for May dipped six cents to 84.77 dollars a barrel.
News that makes sense
Your trusted source for staying up-to-date with the world around you. Get free daily news updates and analysis, straight to your inbox.
The New York oil market had a "fairly quiet" session as prices drifted higher and lower, said Antoine Halff of Newedge Group.
"Perhaps one is seeing merely a correction from the gains of the past two weeks," he said.
"Demand remains weak, the petroleum product inventories is growing -- the fundamentals, which had begun to firm up slightly in the beginning of the year seem to be deteriorating once again," he said.
Oil futures continued their retreat from a peak reached last Tuesday above 87 dollars for the first time since October 2008.
The US government's weekly oil stockpiles report last Wednesday showed an increase in crude oil reserves for the 10th week in a row.
"The sentiment pendulum has shifted temporarily back towards skepticism that demand has not sufficiently recovered to support current prices," said Mike Fitzpatrick at MF Global.
"Last week's inventory reports can, at best, only be read as indicating the energy market remains fragile."
In earlier trading, oil prices gained a boost from a report on Saturday showing that oil imports grew in China, the world's second-largest energy consumer, by 29 percent in March compared with a year earlier.
China imported 4.98 million barrels a day, according to preliminary data from the General Administration of Customs, while net imports were 20.8 million metric tonnes.
"Oil prices are buoyed by the strength in Chinese" data, said Barclays Capital analyst Amrita Sen.
"We expect Chinese oil demand growth to be the greatest contributor to global oil demand growth this year at 0.62 million barrels a day, just shy of the 0.9 mb/d year-on-year growth achieved at the peak of the Chinese oil demand shock in 2004," said Sen.
