I talked with my isuzu mechanic (a good one) about this problem happening with so many owners. Through the years he has noticed two culprits showing up again and again. The EGR and the PCV both linked to oil consumption. Bob (Green Dragon) has an old post talking about the hazards caused by a faulty EGR.

I have been lucky that my VX doesnt use a drop of oil between changes. I do discuss with my mechanic what's going on with forum members VX's. He once made the point of saying for owners to be very careful about buying aftermarket PCV's.