U.S. oil settled lower as traders and investors speculated OPEC producers might surprise with an output cut above what market players expect when the producer group meets this week.
A extension to Iran's nuclear talks, which maintains Western sanctions preventing Tehran from freely exporting its oil, also limited the market's downside, traders said.
Last week, oil prices notched their first weekly gain in two months. On Monday, benchmark Brent crude oil's front-month contract was last down 54 cents at $80 a barrel , trading between a session low of $79.75 and high of $80.85.
U.S. crude futures for settled 73 cents lower at $75.78