Brent crude futures for December delivery were at $42.94 a barrel, down 22 cents, or 0.5%, as of 0035 GMT, while December U.S. West Texas Intermediate (WTI) crude futures slipped 23 cents, or 0.7%, to $41.47 a barrel.
Brent crude futures fell 30 cents, or 0.7%, to $42.32 a barrel by 0149 GMT, after falling 31 cents on Monday.
The return of supply comes as resurgent COVID-19 infections in the U.S. Midwest and Europe raise worries about fuel demand growth, posing a challenge for the Organization of Petroleum Exporting Countries and its allies, together called OPEC+.
Brent crude for December fell 55 cents, or 1.3%, to $42.30 a barrel by 0023 GMT and U.S. West Texas Intermediate for November was at $40.08 a barrel, down 52 cents, or 1.3%.
U.S. West Texas Intermediate (WTI) crude oil futures fell 87 cents, or 2.1%, to $39.80 a barrel by 0104 GMT while Brent crude futures fell by 74 cents, or 1.7%, to $41.91 a barrel.
Trump's health update eased political uncertainty in global markets, pushing Brent up to $39.79 a barrel by 0140 GMT, gaining 52 cents or 1.3%. U.S. West Texas Intermediate (WTI) crude was at $37.64 a barrel, up 59 cents, or 1.6%.
Brent crude slipped on the news and was down 78 cents, or 1.9%, at $40.53 a barrel at 0516 GMT. U.S. oil was 79 cents, or 2%, lower at $37.93.
Brent crude was down 36 cents, or 0.9%, at $40.57 a barrel at 0055 GMT, after falling more than 3% on Thursday. U.S. oil was also 36 cents, or 0.9%, lower at $38.36, having fallen nearly 4% in the previous session.
Brent crude dropped 23 cents, or 0.6%, to $41.03 per barrel by 0048 GMT. West Texas Intermediate fell 26 cents, or 0.7%, to $39.29.
U.S. West Texas Intermediate (WTI) crude futures slipped 17 cents, or 0.4%, to $40.43 at 0120 GMT, while Brent crude futures also fell 17 cents, or 0.4%, to $42.26 a barrel. Both benchmarks rose about 1% on Monday.
Brent crude fell 23 cents, or 0.6%, to $41.69 a barrel by 0243 GMT after dropping 2.9% last week. U.S. West Texas Intermediate was at $40.04 a barrel, down 21 cents or 0.5%, following a 2.1% decline last week.
Brent crude was down 2 cents at $41.92 a barrel by 0113 GMT, while U.S. West Texas Intermediate (WTI) crude was 3 cents firmer at $40.34.
Those fears prompted a rally in the dollar as investors turned to safer assets, adding pressure to oil prices. A stronger dollar makes oil, priced in U.S. dollars, less attractive to global buyers.
Authorities in the United States and Brazil are investigating improper payments to officials at Petrobras, Brazil's state-run oil company, as part of Brazil's far-reaching corruption probe, known as Car Wash. The latest U.S. court filings shed new light on the role of energy traders in a scheme that has led to charges against hundreds of powerful business leaders and politicians.
U.S. West Texas Intermediate (WTI) crude futures for October, due to expire on Tuesday, rose 26 cents, or 0.7%, to $39.57 a barrel at 0224 GMT. The more active November contract rose 15 cents, or 0.4%, to $39.69.
Brent crude was down 20 cents, or 0.5%, at $42.95 a barrel by 0039 GMT, while U.S. crude fell by 27 cents, or 0.7%, to $40.84 a barrel.
Brent crude was down 6 cents at $43.24 a barrel by 0112 GMT, while U.S. oil futures dropped 6 cents to $40.91 a barrel. Both contracts have risen sharply this week as Hurricane Sally cut U.S. production and are on track for a weekly gain of around 9%, the first in three weeks.
U.S. West Texas Intermediate (WTI) crude futures were flat at $40.16 a barrel at 0118 GMT, after jumping 4.9% on Wednesday.
Brent crude was trading up 15 cents, or 0.4%, at $40.68 a barrel by 0055 GMT, while U.S. crude gained 18 cents, or 0.5%, to $38.46 a barrel. Both contracts rose by more than 2% on Tuesday.
Brent crude was down 5 cents, or 0.1%, at $39.56 a barrel by 0407 GMT, while U.S. West Texas Intermediate (WTI) crude futures were down 3 cents, or 0.1%, at $37.23 a barrel.
U.S. West Texas Intermediate (WTI) crude futures were up 9 cents, or 0.2%, at $37.42 a barrel by around 0050 GMT. Brent crude was down 3 cents at $39.80 a barrel.
U.S. West Texas Intermediate (WTI) crude futures fell 20 cents, or 0.5%, to $37.85 a barrel at 0056 GMT, after climbing 3.5% on Wednesday.
The biggest global health crisis in a century continues to flare unabated with cases rising in India, Great Britain, Spain and several parts of the United States, where the infection rate has not come under control for months.
Coronavirus cases rose in 22 of the 50 U.S. states, a Reuters analysis showed, on the holiday weekend traditionally filled with gatherings to mark the end of summer. At the same time cases are flaring up in India and Britain.
Brent crude was at $41.75 a barrel, down 91 cents or 2.1% by 0000 GMT, after it earlier slid to $41.51, its lowest since July 30.