Expectations of a buildup in petroleum supplies in the nation's storage tanks sent oil futures prices tumbling Tuesday on the New York Mercantile Exchange. Analysts said investors sold energy contracts ahead of the American Petroleum Institute's weekly inventory report, which was released after the close of trading. The report showed, as investors expected, increases in heating oil and gasoline stocks. Crude oil supplies declined. In trading on the New York Merc, the March contract for West Texas Intermediate, the main grade of U.S. crude oil, fell 17 cents to $21.60 per 42-gallon barrel. The April crude oil contract declined 13 cents to $21.02 and May lost 12 cents to $20.63. Among refined products, heating oil for February delivery fell 1.71 cents to 59.28 cents a gallon, March declined 0.93 cent to 57.07 cents and April ended 0.32 cent lower at 55.18 cents a gallon. Wholesale unleaded gasoline for February delivery dropped 1.02 cents to 59.62 cents a gallon, while March lost 0.74 cent to 60.58 cents and April slipped 0.43 cent to 61.51 cents a gallon. Analysts said imports and continued strong refinery output in the face of weakening demand contributed to the buildup in energy inventories. ``Looks like a lack of demand for heating oil because of the warmer weather,'' said Tom Bentz, director of futures trading for United Energy Inc. ``On crude, it's imports and refinery runs.'' According to the API, a trade association representing mainly large oil refiners, gasoline stocks rose 4.6 million barrels in the week ended Jan. 19 to 219.5 million barrels; heating oil stocks rose 3.4 million barrels to 111.8 million; and crude oil declined 1 million barrels to 344 million. Most of the decrease in crude oil was from one geographic area, while inventories in other regions rose, analysts said.