U.S. crude futures extended losses after inventories unexpectedly surged last week as imports jumped and refineries maintained output.
US crude settled about 1 percent lower, but a possible a deal between Iran and world powers offset supply shocks in the Middle East.
Brent crude oil slipped below $87 a barrel on Thursday as expectations that U.S. interest rates may rise sooner than previously thought pushed the dollar higher.
Brent crude fell below $86 a barrel on Friday on news of strong supply from OPEC producers and as a case of Ebola in New York spooked equities markets.
Brent crude oil rose above $86 a barrel on Friday, bouncing from near four-year lows as investors bought back into a market they said was oversold
Brent crude futures fell as lower economic growth forecasts raised concerns about global oil demand amid rising U.S. inventory levels.
Crude reversed session gains, after the effect of U.S. stockpile data wore off and investors grew fearful about growing risks.
Crude reversed a steep drop, boosting both Brent and U.S. oil after data showed a surprise drop in U.S. inventories.
Crude rose as violence in Ukraine kept markets on edge, but prices remained on track for a monthly loss amid ample supply and weak demand.
Oil pulled away from multi-month lows, as a drop in U.S. oil inventories momentarily overrode concerns about ample supplies.
Crude rose in choppy trading, with Brent recovering from a 13-month low as turmoil abroad kept concerns about potential supply disruptions in focus.
U.S. oil ended at a new 6 month low despite data showing a further decline in oil stockpiles and a steep drop in gasoline inventories.
Oil prices fell, as traders booked profit in the wake of Ukraine's election, with the dip expected to be short-lived.
Crude fell on Monday, pressured by reports that China's manufacturing sector contracted and Libya's oil output was recovering.