Doubts about demand for oil are raised as the outlook for Eurozone's future is getting cloudier, pushing oil prices lower. Crude oil for September settlement dropped 3.9 per cent, to $88.28 per barrel, while the ICE dollar index increased by 0.35 per cent to 83.908. Moreover other oil related products, also declined on Monday. August heating-oil tumbled 3.3 per cent, to $2.83 per gallon, gasoline for August delivery erased 3.2 per cent to $2.85 a gallon and August natural gas declined 0.6 per cent, to $3.06 a million British thermal units.