Worries about the health of the global economy and gains for the U.S. dollar sent crude oil futures lower Thursday in New York. Light, sweet crude for November delivery dropped $4.56 to $93.97 a barrel on the New York Mercantile Exchange, and Brent crude fell $4.77 to $90.56 a barrel. Reformulated gasoline futures declined by 11 cents to $2.26 a gallon, and heating oil slid 14 cents to $2.71 a gallon. Among stocks, integrated oil and gas companies Exxon Mobil ( XOM), Chevron ( CVX) and ConocoPhillips ( COP) all saw their shares fall. Refiners Valero ( VLO) and Tesoro ( TSO) gave back more than 11% each. Services names Halliburton ( HAL) and Schlumberger ( SLB) also declined. The U.S. Oil ( USO) ETF, which tracks crude prices, slid 4.7%.