My freelander 54 plate has oil in just about everything in the engine a thick grey mayo when drained oil into a bucket gave it a stir it turned grey, the head has been removed but the head gasket looks ok,there was no overheating exhaust was dry just black it was running ok till this happened, a new oil cooler was fitted march 22 I have no clue as what it could be

The head gasket never goes on a TD4.
However the oil cooler or its seals can leak causing fluids to mix. This is pretty common on lots of cars including the TD4.

As above which John has highlighted click this link it should help, cheap orange juice is good for flushing out the mayo, you may have to flush the engine a few time to remove all of it.