Oil fell 2 percent in volatile trading on Thursday, as support from a weakening dollar was overshadowed by skepticism that cash-strapped OPEC member Venezuela's effort to lobby crude producers for joint output cuts would succeed.
The dollar extended its drop for a second day, making greenback-denominated commodities cheaper for holders of other currencies, with the dollar index hitting a roughly 15-week low on continued doubts that the Federal Reserve would be able to hike interest rates this year.
After settling down, US oil pared losses slightly, but held lower, after a report that the White House might include a $10 per barrel oil fee in a 2017 budget proposal.
Brent crude settled 1.6 percent, or 58 cents, lower at $34.46 a barrel, after trading between $34.15 and $35.84. It was last trading down 60 cents at $34.44.
U.S. crude also ended lower, down 56 cents, or 1.7 percent, at $31.72 after swinging between $31.53 and $33.60. WTI was last down 54 cents at $31.74.