I've noticed a couple of times now that after going down hill using engine breaking when I then accelerate at the bottom of the hill I put out a large plume of burnt oil blue smoke. I know it's not the turbo as that's just been replaced, am I right in thinking it's likely to be valve stem oil seals? If so I remember seeing a post about rebuilt gas flowed heads but can't remember who does them and how much any one have any ideas. My car is a 2005 2.4 v70 t5 ex plod which now has 282k on the clock.