Brent crude for October delivery fell US$0.58 to $US50.10 after ending the previous session 18 cents higher.
Brent rose as high as US$50.87 a barrel earlier in the session.
U.S. crude for October delivery, also known as West Texas Intermediate, was down 66 cents at $US46.09 a barrel, off the day’s high of $46.85. It settled up 50 cents on Thursday.
US Trade Deficit Continues To Show Decline
Official figures show the U.S. trade deficit with the rest of the world fell to a five-month low in July.
The U.S. Commerce Department said it declined 7.4% to $41.9 billion, compared with $45.2 billion in June.
The trade deficit represents the difference between the value of what the U.S. exports to the rest of the world and what it imports.
Exports rose 0.4% to $188 billion, helped by stronger global sales of American cars.
Imports fell 1.1% to $230.4 billion dollars.