Crude fell in Asian trade as a firmer dollar discouraged investors from buying oil futures.
US crude for December delivery fell $1.57 to $86.24 a barrel.
Brent North Sea crude for December dropped 1.31 dollars to 87.50 dollars a barrel.
A firmer greenback makes it more expensive for investors holding other currencies to buy dollar-denominated commodities including oil futures.
Crude prices have risen in recent sessions, pressured by the weak dollar.
Meanwhile, OPEC latest revised upward its world oil demand growth estimates for this year and 2011 amid cautious optimism about the global economic outlook.
The Organization of the Petroleum Exporting Countries (OPEC) OPEC said it was pencilling in world oil demand growth of 1.3 million barrels a day for 2010, up 190,000 barrels from its previous estimate.
OPEC pumps 40% of the world's crude.
