Strong demand in the United States has been supporting prices. The U.S. Energy Information Administration reported record gasoline demand of 9.84 million barrels per day (bpd) for last week, and a fall in commercial crude inventories of 1.5 million barrels to 481.9 million barrels.
That's below levels seen this time last year, an indication of a tightening U.S. market.
"Five weeks of crude draws is lending some credence to the idea that the OPEC cut is beginning to impact the market," said Gene McGillian, manager of market research at Tradition Energy in Stamford.
Still, U.S. light crude has been capped by robust domestic supplies.
"The market needs continuing signs of improvement in the inventory picture to really drive the prices higher," he said.
But traders say high production by the Organization of the Petroleum Exporting Countries is capping prices.
OPEC and other producers including Russia have promised to restrict output by 1.8 million bpd until March 2018 to help support prices and draw down inventories.
Yet OPEC output hit a 2017 high of 33 million bpd in July, up 90,000 bpd from the previous month, a Reuters survey showed earlier this week, led by a further recovery in supply from Libya, one of the countries exempt from a production-cutting deal.