New York's main contract, West Texas Intermediate (WTI) light sweet crude for July delivery, fell 59 cents to $94.36 a barrel.
Brent North Sea crude for August shed 57 cents to $113.45.
Traders deserted crude after a bargain hunting spree on Wednesday as fears of a prolonged debt crisis in the eurozone came to the fore yet again, said Ker Chung Yang, a commodity analyst for Phillip Futures in Singapore.
"There's no solution in the European crisis so I think this will still affect the crude market," he told AFP.
Tensions were rising over the state of the European economy as debt-addled Greece prepared to name a new government after two senior officials quit on Friday.
Prime Minister George Papandreou on Thursday appealed for unity from his own lawmakers as the International Monetary Fund (IMF) insisted there could be no backsliding on agreed austerity measures.
French President Nicolas Sarkozy is due to travel to Berlin later Friday to meet German Chancellor Angela Merkel for crisis talks on the eurozone economy.
Crude markets have recently been rattled by the failure of eurozone finance ministers to reach an deal on a second bailout package aimed at averting a Greek debt default, which could plunge financial markets into crisis.
