could be a busted piston ring or a valve stem seal... either way it means taking the engine to bits (or maybe even a new engine if its the worst case scenario of a broken valve).
drain and have a look at the oil from the engine.. is there any little bits of metal in it? if so very bad news. if not then it could just be the stem seals.
if you are not VERY sure about what you are doing take it to a garage you trust, or if it runs sell it quick.
Hope this helps.
eab, February 2006
