The turbo recon company swapped it out out for me. This one is passing a lot less oil. It's much more responsive too. I put a boost gauge in when I was suspicious of the other one, the needle responds much more rapidly now. The old one didn't spin very easily, when you spun the blades with your finger it was 'sticky'. The new one spun much more freely. She's pulling very well, is quiet and smooth compared to before the rebuild. The engine still smokes for a few minutes from cold, but it seems to be using less and less oil each week. So, I'm going to see how it goes for another two or three thousand miles, perhaps more cos the winter will kick in. I'm hoping it's 'running in'. If it's still smoking then I'll have to think about re-honing the bores as James Martin suggested. If I end up doing that it'll have to wait until next spring when the weather warms up as I've just the drive to work on and it's gets canny cold up here.