International benchmark Brent crude traded at $53.38 per barrel at 11.08 GMT on Friday, while American benchmark West Texas Intermediate (WTI) saw prices of $45.44 per barrel, marking losses for both prices since Monday's opening.
Brent crude started the week at $55.51 per barrel at 05.37 GMT on Monday, while WTI saw prices of $45.96 per barrel.
Monday's gains were the result of expectations that the low prices could push U.S. shale production downwards as the current prices would render shale production more costly.
However, experts believe that the market players are still worried about the global economic outlook amid the global trade wars, especially between China and the U.S.
On Wednesday, crude oil prices opened mixed Wednesday to rebound from major losses as the glut of supply in the global market continues to worry investors.
Brent crude was trading at $50.58 per barrel at 06.20 GMT with a 0.2 percent daily gain after closing Monday at $50.47 a barrel. Additionally, WTI was at $42.74 a barrel at the same time for a 1 percent loss, after previously closing at $43.16 per barrel.
On Thursday, crude oil prices were down after they jumped more than 7 percent in the previous session with major indexes in the U.S. stock market posting historic gains.
By Gulsen Cagatay
Anadolu Agency
energy@aa.com.tr