Oil prices were lower in quiet Asian trade Friday as traders took a break during the US Thanksgiving holiday season, analysts said.
New York's main contract, light sweet crude for January delivery, slid 23 cents to $83.63 per barrel in the afternoon.
Brent North Sea crude for January fell 56 cents to $85.54.
Crude prices have traded in a tight range since Thursday as the Thanksgiving holiday weekend commenced in the United States, said Serene Lim, oil and gas analyst at ANZ bank in Singapore.
"It's going to remain rangebound today probably because of yesterday's Thanksgiving holidays," she told AFP. The four-day festive holiday ends this Sunday.
However, Lim warned that crude markets were still depressed by "persistent worries" over the risk of debt contagion in the eurozone amid talks to bailout debt-ridden Ireland.
Having built up a deficit equivalent to 32 per cent of gross domestic product this year, Ireland is in negotiations to borrow about 85 billion euros ($114 billion) from the European Union and the International Monetary Fund.
The talks on the bailout are expected to wrap up on Sunday.
The intervention has failed to remove doubts about Ireland's ability to stabilise its shattered finances and has sparked concerns for the wider eurozone.