Oil rose in Asian trade today but the gains were seen as brief amid ongoing concerns over the eurozone debt crisis, analysts said.
The dollar's strength against the euro is also likely to be a factor in pressuring crude prices downwards, they said.
In morning trade, New York's main contract, light sweet crude for January delivery gained 14 cents to $83.90 a barrel.
Brent North Sea crude for January delivery fell eight cents to $85.50.
"Oil and the dollar have an inverse relationship so we could see some downward pressure on oil if the dollar continues to rise," said Ong Yi Ling, Phillip Futures' investment analyst.
A stronger dollar makes dollar-priced crude more expensive for buyers using weaker currencies and that in turn tends to hit demand and prices.
"Another factor will be the eurozone debt crisis... That could affect future demand for oil," she told AFP.
The euro fell to a fresh two-month low of $1.3181 during Asian trade, its weakest level since late September as investors remain worried about the eurozone's worsening debt crisis.
Eyes were also on Portugal and Spain amid speculation they may need bailouts after debt-ridden Ireland said it will receive an 85-billion-euro package from the European Union and the International Monetary Fund.