I will let you know if I find out what mine is, but when I did head bores looked ok no grooves, I had all new guides and seals and then I replaced turbo with recon exchange. It still uses same amount of oil, I have an uprated breather fitted and have taken all this apart and I am getting no oil in there at all. I am only guessing that my oil control rings are gone but compression rings are ok, as all are even with a compression test, but am going to get it looked at before I take it apart, but it is the only part of the engine left that has not been done so I am fairly confident, as I cannot see what else it could be. I am just passing on my expereince as I was disapointed after I followed advice I was given only to find it made no difference. Although when I took head off the guides were well worn so the job was needed.
Also turbo does have quite a lot of play side to side even when new.