By Ayesha Rascoe WASHINGTON, Nov 29 (Reuters) - U.S. oil demand in September was weaker than previously estimated, as demand for gasoline and distillate fuels declined steeply, the U.S. government said on Thursday. The Energy Information Administration said in its Petroleum Supply Monthly report that oil demand for the world's top consumer fell to 18.173 million barrels per day from last year, down 218,000 bpd from a previous projection. That downward revision placed oil demand off 719,000 bpd, or 3.81 percent, from the 18.892 million bpd posted for the month last year. The EIA had initially forecast a 2.65 percent decline year-on-year. The EIA's demand figure for September was nearly identical to the 18.182 million bpd reported by the American Petroleum Institute for the month. API also said demand fell 3.8 percent from a year ago. Demand for petroleum products was weak in September, with U.S. gasoline use falling 1.93 percent from a year ago. Distillate fuel consumption dropped 6.48 percent from last year, while jet fuel demand fell 2.61 percent. EIA Monthly Demand Data Product September Prev Est Prev Est Yr Ago Yr Ago Pct For Sept Pct Change Change Gasoline 8.575 8.673 -1.13% 8.744 -1.93% Distillate 3.681 3.715 -0.92% 3.936 -6.48% Jet Fuel 1.379 1.424 -3.16% 1.416 -2.61% Residual 0.302 0.321 -5.92% 0.491 -38.49% Total 18.173 18.391 -1.19% 18.892 -3.81% U.S. year on year oil demand changes: August 2012 -0.97 pct July 2012 -0.94 pct June 2012 -1.76 pct May 2012 1.23 pct April 2012 -1.72 pct March 2012 -5.77 pct Feb 2012 -0.6 pct Jan 2012 -3.75 pct Dec 2011 -4.66 pct Nov 2011 0.54 pct Oct 2011 -0.69 pct -This chart compares the latest monthly EIA petroleum supply report with the previous weekly report and final year-ago numbers. The EIA's monthly report always differs from the weekly report as the monthly reflects data supplied from all U.S. energy companies, while the weekly report surveys the biggest companies representing about 90 percent of the market. The total demand number reflects many petroleum products beyond gasoline, distillate, jet fuel and residual fuel listed in the table.