Oil rose towards $78 on Thursday as the United States, the world's biggest energy consumer, was expected to return to economic growth, but gains were limited by the weakness of fuel demand in the near term.
U.S. crude oil futures rose 19 cents to $77.65 a barrel by 1214 GMT. London Brent crude rose 26 cents to $76.12.
Economists predict the U.S. government's advance estimate will show GDP grew 3.3 percent in the third quarter, the first growth since early 2008. The gross domestic product data will be published at 1230 GMT.
A recovery in the world's largest economy should raise energy demand, which has been crushed by the economic crisis over the past year.
"Fundamentals have not really changed over the last three or four weeks. We were at $70 a barrel before and now we're at $80," Petromatrix analyst Olivier Jakob said.
"We are in an environment with very high speculative investment."
Analysts said investors were pushing oil prices higher due to long-term expectations rising energy demand will see crude markets tighten in the coming years.
Crude prices have more than doubled since the turn of the year, but are only around half the peak hit close to $150 a barrel in July 2008, when booming demand from powerhouses like China sparked fears supplies may struggle to keep up.
DOES A WEAK DOLLAR TRUMP WEAK DEMAND?
Weakness in the U.S. dollar has also been supporting commodity prices, as investors turn to hard assets as a hedge against inflation. Dollar-prices commodities also become cheaper for holders of other currencies.
The euro rose against the dollar on Thursday, reversing four days of losses seen after the greenback had slumped to a 14-month low of $1.50 against the single currency last week.
"Right now, we're in an environment which is a global market," said Michael Lewis, Deutsche Bank's head of commodity research. "You don't have diversification any more between equities, crude oil and the dollar."
But weak demand for oil is keeping a lid on price gains.
On Wednesday, official weekly U.S. oil data showed a sharp increase in gasoline inventories. Total oil product demand dropped by about 3 percent from a year earlier.
