Oil headed for its biggest quarterly drop in New York since the 2008 financial crisis as signs of slowing growth in China, the US and Germany heightened concerns that fuel demand will suffer. West Texas Intermediate futures fell 15 per cent last quarter, the biggest drop since the three months ended December 31, 2008. Chinese manufacturing fell for a third month, according to data from HSBC Holdings Plc, while Germany\'s Federal Statistics office said retail sales declined the most in more than four months in August. US consumer spending slowed in August as incomes declined, the Commerce Department said. WTI\'s discount to Brent oil narrowed for a sixth day, the longest streak since March 2010. \"There is a risk of slowdown in Chinese demand,\" said Eugen Weinberg, head of commodities research at Commerzbank AG in Frankfurt, who forecasts Brent prices at $100 in this quarter. \"The risks to the forecast in the fourth quarter and for 2012 as a whole are to the downside.\" Libya output Crude for November delivery on the New York Mercantile Exchange fell as much as $1.59 (Dh5.83), or 1.9 per cent, to $80.55 a barrel and was at $80.64 at 1:52pm London time. WTI was down 9.2 per cent last month. Brent oil November settlement fell $1.57 to $102.38 a barrel on the ICE Futures Europe exchange in London. Prices were down 9 per cent last quarter. Brent\'s premium to WTI futures narrowed to $21.74 a barrel from $21.81 at settlement on Thursday. The spread climbed to a record of $26.87 on September 6 as fighting in Libya reduced the availability of light, sweet crude, or oil with low density and sulfur content. Libya is now producing 300,000 barrels a day of oil, said Ali Tarhouni, the official in charge of the finance and oil ministries, on Thursday.]