In a medium saucepan, over low heat, combine turkey neck, celery leaves, carrot top, onion and water to cover. Simmer for 2 hours as the turkey roasts. In a large bowl combine stale breads, set aside. In a large saute pan melt butter with vegetable oil. Add onions, celery and sage and cook over medium heat until onions begin to brown Add onion mixture and enough of the giblet broth to moisten bread, toss, and set aside. About 1 hour before the turkey is done, using a turkey baster or a large spoon remove all but 1/2 cup of fat from pan. Toss the oysters with the bread stuffing and add it in an even layer to the roasting pan with the turkey, stirring to coat the bread. Return the turkey to the oven and continue roasting for the final hour. Serve as a side dish.