Prices are rising on hopes that Washington and Beijing could resolve their trade disputes, which have dented global economic growth.
Gasoline stockpiles climb 7.5 million barrels, far exceeding analyst expectations for a 2.8 million-barrel gain.
Concerns about slowing global economic growth have dampened investor demand for riskier asset classes and pressured crude futures.
Opec's biggest problem is surging production in the United States, where output has grown by around 2 million bpd in a year to more than 11.5 million bpd.
Oil, which closed at a seven-month low in New York on Tuesday, slipped further after an industry report was said to show a larger-than-expected increase in US crude inventories.
Oil is also being weighed down by signs of rising supply from top producers.
Saudi Arabia has already boosted its daily output to well over 10.5 million bpd to meet rising demand in the wake of several production disruptions in other countries.
Oil prices edged up as markets were expected to tighten once US sanctions against Iran's crude exports are implemented next month.
US crude stockpiles were forecast to have risen for the fourth straight week by about 1.1 million barrels in the week ended Oct 12.
Saudi Arabia has been under pressure since Jamal Khashoggi, a prominent critic of Riyadh and a US resident, disappeared on Oct 2 after visiting the Saudi consulate in Istanbul.
Limited spare production to deal with further supply disruptions means the capacity is quickly declining due it Asia's insatiable demand.
Implied volatility for very bullish Brent options that expire after the Nov 4 resumption of sanctions has overtaken that for very bearish options, suggesting increased demand for such bullish bets.
Traders said global oil markets remained tense because of the looming US sanctions against Iran's oil exports, which kick in from Nov 4.
When oil prices declined in 2014, many governments including India and Indonesia, increased fuel taxes or removed subsidies leading to record high retail fuel prices as crude prices rose.
Concerns over tightening supplies are growing as more buyers of Iranian crude shun purchases from the Islamic Republic before US sanctions take full effect in early November.
The long-awaited yuan-denominated contract debuted in March with a plan to increase China’s influence over pricing as well as promote the use of its currency in international commerce.
The company, which develops small oil and gas fields in Asia, has two major producing assets.
Crude oil prices could rise to US$90 per barrel by Christmas and to US$100 by the New Year as markets tighten.