About four years ago ran the P18 with 200 2.4 alongside the revenger 27 with 502mpi from Poole to Yarmouth to Bucklers hard in smooth seas running hard and when we fueled at bucklers both took to within a litre of each other!
Ran hard back against wind tide and pestilance and the Phantom used shedloads more fuel than the Revenger as she was cruising whilst the Phantom was finding it hard work.
Both my boats so no axe to grind. Loved 'em both but the phantom finally had to go when I blew the engine to pieces after 1600 hours from new!
So the answer is pretty well the same depending on what your doing but no oil needed on the inboard