sounds even worst then, if it was a normal oil leak from a gasket of seal then youll just see a puddle of oil but no burning of said oil, if youve had blue smoke then its burning it from somewhere and the fact your engine was empty isnt good news, the oils had to of gone somewhere !!!!????!!!!.

when mine smoked it was only when i left it over night and itll only appear after about 10mins when warm, as i said it turned out to be the turbo so i assume oil was bypassing the oil seals etc inside which caused it to burn off.......i reckon you should give it a few over night start ups before assuming alls ok mate coz as said before, oil doesnt just disappear for no reason bud.

dave