MY93 wrx import.It has a misfiring engine,oil is burning from the wastegate area and dump valve/blue smoke from tailpipe,I had it look at and was told it was turbo problems but since then I checked to see if it could be the piston or valve causing it,by removing the oil filler cap and slight revs up about 2k,blue oil smoke was coming from the oil filler and the oil level was very low
So is this a piston problem or is the turbo a dud??

 

id say an engine prob mate...take of the headers and look up into the chambers, if there covered in oil then u know its then, they should be dry and coacked up

 

Have a look in the boost pipe from the turbo before the intercooler, if this has a large coating of oil inside them then this could point to a problem with your turbo.

Also worth checking your oil does not get too low.

If no oil is the boost pipe as suggest look towards the engine.

 

I had the same problem mate if you run the engine but take one of the 2 head breather pipes out of the air intake pipe and see if it smokes a lot if it dose more than likely the engine not the turbo. after having a few silly quotes to have the engine fixed i opted for the 2.5 short block with my heads oni think the block was £1600 brand new and has more grunt lower down as well as on full boost