New York's main contract, West Texas Intermediate (WTI) crude for delivery in July, rose 76 cents to close at $90.66 a barrel.
The WTI futures contract had hit $89.90 on Wednesday, its lowest level since October.
In London trade, Brent North Sea crude for July gained 99 cents to $106.55, after tumbling almost $3 the previous day to a five-month low.
Matt Smith at Summit Energy said the markets were taking a breather after being hammered by negative news of late, particularly from Europe.
The fact that WTI has topped $90 gives "a bit of hope" to investors who have watched the contract shed $16 in the past three weeks.
The slight bounce in optimism was underpinned by a European Union summit late Wednesday. The 27 member countries are "looking to save Greece, so that brought a lot of support there," Smith said.
In Baghdad, two days of tough talks aimed at helping resolve the stand-off between major oil producer Iran and major economies over Tehran's nuclear program wound up Thursday with no significant progress.
Major powers Britain, China, France, Russia and the United States plus Germany tabled a proposal that included sweeteners to persuade Iran to abandon enriching uranium but Tehran balked at the offer.
Iran has faced crippling sanctions over its nuclear program, which much of the international community believe is masking a push to develop atomic weapons.
Tehran denies the claims.
The parties agreed to meet again in Moscow on June 18-19, said EU foreign policy chief Catherine Ashton.
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