The 43c fall in New York's Western Texas Intermediate to $US76.65 a barrel came after the US Federal Reserve said US factory output fell 0.4% in June, while the Federal Reserve Bank of New York reported its general economic index fell 5.1 points in July from 19.6 points in May.
China also reported reduced growth, with the country's economic growth rate easing 10.3% in the second quarter.
"We believe that international economic recovery will continue but it will be a fairly rocky road," Commonwealth Bank of Australia analyst David Moore told Reuters.
MFC Global Investment Management senior managing director Chip Hodge told Bloomberg prices would stay in the $70/bbl range until there was solid economic growth.
Singapore's Tapis crude remained unaffected by the news, rising from $80.39/bbl on Wednesday to $81.03 last night.
As for commodities, copper experienced a topsy turvy week, with three-month delivery prices dropping from $6710 per tonne on July 9 to $6610/t on July 13 before bouncing back to $6712.50/t the next day. Prices overnight on the London Metal Exchange once again dropped back to $6680/t.
Barclays Capital said the copper market remains subdued, indicating a lack of investor interest, while physical demand is good, with some tonnage being booked in Asian warehouses at a $77 premium and more demand expected, which should keep the market in its current range of $6500-$6800/t.
Nickel prices had a more solid run for the week, going from $19,190/t on July 9 to reach its highest point of $19,500/t on Wednesday. It closed overnight at $19,400/t.
Spot gold tracked back to its previous weekly price overnight of $1208 per ounce, coming off an intra-week high of $1216/oz.
Investor safe-haven demand for gold provides significant price support and will do so for the next three months, "probably even lifting moderately from current levels," Down Jones Newswires cited the Commonwealth Bank of Australia as saying in a daily note.
However, the bank also noted a fall in the gold price over 2011, as progress towards international economic recovery erodes gold's safe-haven allure.