But analysts and officials said some Gulf states were pressing for a small but symbolic increase of 500,000 barrels a day to reassure the markets.
Light, sweet crude for October delivery lost 35 cents to $76.35 a barrel in trading on the New York Mercantile Exchange, while October Brent crude fell 44 cents to $74.63 a barrel on the ICE Futures exchange in London.
Silence from Saudis
Saudi Arabia, OPEC's No. 1 producer and most influential member in the 12-nation group, was the wild card. The oil-rich kingdom made no public statements Monday, adding a touch of suspense heading into Tuesday's deliberations.
"This could be either the most uneventful OPEC meeting ever, or they may come with something up their sleeves," said analyst John Hall of London-based John Hall Associates.
Even if OPEC boosts crude output, the higher quota wouldn't necessarily mean an increase in actual oil on the market because the cartel already is pumping well over its target.
Recent surveys of output by the 10 members that are bound by the quota -- excluding Angola and Iraq -- suggest the group is producing closer to 30.3 million barrels a day.
And crude oil needs refining, which can mean a holdup of at least 40 days, said Eshan Ul-Haq, chief analyst for Vienna's PVM Oil Associates.
"It all takes time," said Ul-Haq, who estimates OPEC has a spare capacity of up to 3.15 million barrels a day.
"Even if they increase production, it could be too late" for deliveries of home heating oil for customers facing the approach of winter in the Northern Hemisphere, he said.
Ul-Haq also noted that the United Arab Emirates is scheduled to perform maintenance on its oilfields next month, and that the work would force it to cut production by roughly 400,000 barrels a day -- at least temporarily negating any 500,000-barrel increase.
With oil prices hovering around $76 a barrel, pressure has built on OPEC to intervene. Crude hit a record $78.77 a barrel in early August on the Nymex, and many market-watchers see $80 as the new threshold.
The Paris-based International Energy Agency repeatedly has urged the group to raise crude output at this week's meeting, arguing that global demand is likely to outstrip supply with the advent of winter.
But many OPEC members said they felt no compulsion to act quickly, since demand for gasoline and diesel fuel has slackened with the end of the summer driving season.
Others said they were still assessing the impact on the global economy of the slump in the U.S. housing market.
With mortgage defaults rising, lenders have tightened conditions on loans to prospective U.S. home buyers, and the slowdown has stoked fears of a recession and reduced demand for oil and gasoline.
If OPEC opts not to boost its output targets Tuesday, analysts said an increase could come before the next OPEC meeting Dec. 5 in the United Arab Emirates.
The 12 OPEC members are Algeria, Angola, Indonesia, Iran, Iraq, Kuwait, Libya, Nigeria, Qatar, Saudi Arabia, United Arab Emirates and Venezuela.