So I just started her up after cleaning off the rear of the engine with gunk to, a) make cleaner work of removing the oil pressure sender and b) hope to fix oil pressure sender without taking it off.
Let the engine running 10 mins, was happily revving up to 5k (do have quite a bad missfire on full throttle from 1k but its stable at 5k) temperature was up to about 95'C.
Oil pressure is around 3 when idle and up to 5 when revved so I'm thinking all is pretty cool.
Turn her off and there are massive sounds of oil bubbling from the front of the head. Traced this to the large oil pipe which feeds the turbo, this hose is mentally hot and you can feel the oil bubbling when you touch it.
So I'm guessing this really isn't too good. Although the turbo wasn't being asked to do any work it shouldn't have been harmed by this, but what's going on?