U.S. crude for October delivery rose $1.17 to $72.27 a barrel by 1545 GMT (11:45 a.m. EDT), adding to Tuesday's gains of more than $3. London Brent rose $1.18 to $70.60.
The dollar fell near the year's low against a basket of currencies, spurring broad buying across commodities markets.
Weakness in the greenback outweighed the strong feeling in the oil market that OPEC ministers meeting in Vienna will keep official output levels unchanged.
It is completely priced in that OPEC will leave output unchanged, said Christopher Bellew, oil broker at Bache Financial. It is going to be gold, the dollar and equities again that will move the market.
Spot gold prices held near $1,000 per ounce on Wednesday and global equities prices also were stronger.
So far, none of the 12 OPEC members has stated any need to cut production as higher prices and signs of a strengthening world economy shift the focus away from sluggish fuel demand.
With the price ranging between $68 and $73, what else do you want? The price, everybody likes, consumers and producers, Saudi Arabian Oil Minister Ali al-Naimi told reporters when asked if OPEC needed to change its output policy.
The group's meeting starts at 1930 GMT (3:30 p.m. EDT).
Soft demand in the United States has forced top refiner Valero to sack hundreds of workers and idle several major processing units.
The market will get a reading on U.S. crude stocks with numbers from the American Petroleum Institute due on Wednesday at 2030 GMT (4:30 p.m. EDT). The U.S. Energy Information Administration will release its data on Thursday at 1500 GMT. Both have been delayed a day by Monday's Labor Day holiday.
A Reuters poll of analysts showed expectations of a 1.5 million barrel drawdown in crude stocks, a 700,000 barrel increase in distillate supplies and a 1.4 million barrel decline in gasoline inventories.
Traders were keeping an eye out as Hurricane Fred formed in the eastern Atlantic Ocean.
(Additional reporting by Nick Trevethan in Singapore and Richard Valdmanis in New York; Editing by David Gregorio)