oil out the dump valve means theres oil getting into the inlet side somewhere and it can be two sorsces,
1 the breather system could be putting oil into the airfilter box via the thick black pipe, so check in the filter box is not full up with oil, if so check the little breather thingy on the l/h side of the inlet plenum as you look at the engine and make sure all the pipes are secure might be no harm to remove it and dip it in petrol and slosh it about to dislodge and caked oil in there,its the bottom short pipe that takes away excess oil in the breather air and routes it to the manifold for burning using vacuum when the throttle is closed
2 this could be a bit more expensive, the turbo oil seals on the compressor side could be leaking causing oil to be blown right through the air pipes and through the intercooler through the crossover duct and into the manifold giving blue smoke out the back,i have seen this type of leak also put oil into the air filter box dur to air being blown back at snap throttle close.
remove the turbo inlet pipe and check for oil in the pipe and the inlet of the turbo,if it there this could be your problem,but i would make sure its nothing else before resorting to removing the turbo,
because the car was lying up for a year the turbo seals may not be at there best,maybe a good roasting on the open road might loosen them up a bit