Oil prices were mixed in choppy trade today as disagreement flared within producer cartel OPEC on who should cut how much production in a planned coordinated reduction to prop up prices.
International Brent crude oil futures fell five cents to $51.41 per barrel from last night's close.
US West Texas Intermediate (WTI) crude futures turned positive, gaining five cents to $50.57 a barrel, in late Asia trade after being negative, falling to a low of $50.37 a barrel, for much of the session.
The dollar, which held near nine-month highs against a basket of major currencie, weighed on prices.
A strong dollar makes greenback-denominated commodities including oil more expensive for holders of other currencies.
Iraq's oil minister Jabar Ali al-Luaibi said on Sunday the second-largest producer in the Organisation of the Petroleum Exporting Countries (OPEC) wanted to be exempt from output curbs as it needed more money to fight Islamic State militants.
Until there is more clarity on the planned cut, which OPEC hopes will be coordinated with non-members like Russia, analysts said oil prices would likely remain range-bound - but volatile - around current levels.
The private American Petroleum Institute (API) is due to publish its weekly crude stocks estimates later today, followed by the official Energy Information Administration (EIA) data due tomorrow.
A Reuters poll showed that US crude inventories were forecast to have risen last week by a likely 800,000 barrels to 469.5 million barrels.
That came after a fall of more than 5 million barrels in the week to October 14. US crude inventory data is closely watched to gauge supply and demand in the world's biggest crude consumer.