Traders are weighing concerns about economic growths that have also hurt the stock market.
News of a possible ceasefire between Turkey and Kurdish rebels in Iraq added to the downward pressure on prices.
The stock market's downturn Friday has reignited concerns about a slowdown, which could cut demand for oil and petroleum products.
Traders are also selling to lock in profits from a rally in which oil futures jumped almost 14 percent in less than two weeks. The November crude contract expires today.
Light, sweet crude for November delivery fell $1.92 to $86.68 a barrel on the New York Mercantile Exchange.