ok we have a 945t (91) with 145k on it...

uses 1ltr oil every 100 or so miles (up if driven hard, less if driven softly)

no external leaks, pcv is clean, turbo replaced, little or no il in the intercoller, pipes etc, one way valve inserted in the the manafold to flame trap hose, new gasket on oil filler no water use, goes like stink, compresion tests ok (perhaps a little down on no 1)runs just fine just uses oil...currently in the wash cycle with auto-rx

now had my brother drive behind me for a while the other day and he confirmed something i thought i knew...it smokes under boost, and I am sure its smoking more than it used too..

what he also told me is that on a descent when the engine is under vacume (this is a manual car and i use a lot of engine breaking) it is also smoking, not as much as under boost but smoking....

at idle it doesnt smoke...rev it on the drive it doesnt smoke...

now I am fairly resigned to this being nasty, the question is how nasty...the options i see are principally (a) warn valve oil seals (b) worn valve guides (c) worn piston rings...

anyone got anything else to add to the list or opinions on the liekly hood of each and the best approach to take ..options I am currently considering:-

1. pull the head, do seals etc
2. repalceth head
3. repalcethe whole engine
4. sell car and buy another 850 (t5???) or s/v 90 as it would seem to me that engine has less issues than most of the b230's i have had to play with - maybe i have just been unlucky but the list of temanaly corrroded engine blocks, oil eaters, weird idel problems etc does make me wonder..