New York's main contract, light sweet crude for delivery in December, gained five cents to $84.93 a barrel.
Brent North Sea crude for December advanced a cent to $86.35 on its last trading day.
Investors bought up crude after it slid more than three percent on Friday, said Serene Lim, oil and gas analyst for ANZ bank in Singapore.
"I think investors are just taking the opportunity of the sell-down last week to buy.... The fall was actually a good opportunity to buy into the market," she said.
Lim added that crude prices of $90 were possible by year's end.
"In general it seems like fundamentals are improving and $90 is possible" by the end of the year, she said.
The International Energy Agency (IEA) on Friday raised its 2010 global oil demand growth forecast to an average of 87.3 million barrels per day, partly due to a stronger-than-expected rebound in the third quarter.
Data from the US Department of Energy released Wednesday also showed crude stockpiles in the world's biggest oil consumer eased 3.3 million barrels in the week ending November 5, compared with forecasts of a 1.4 million-barrel rise.
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