Remove giblets and neck from turkey; rinse giblets and neck thoroughly, and place in a medium saucepan. Add water, and bring to a boil. Reduce heat; cover and simmer 30 minutes. Remove giblets and neck, reserving broth. Discard neck; chop giblets, and set aside.
Rinse turkey thoroughly with cold water, and pat dry. Combine 1 teaspoon salt and 1 teaspoon pepper; sprinkle in cavity of turkey.
Combine bread cubes, cornbread crumbs, onion, celery, eggs, butter, 1 teaspoon salt, 1 teaspoon pepper, sage, reserved broth, and giblets; mix well.
Stuff dressing into cavity of turkey; close with skewers. Tie ends of legs to tail with string or tuck them under band of skin at tail. Lift wingtips up and over back, tucking under bird securely. Place turkey, breast side up, in a roasting pan.
Cover surface of turkey with several layers of cheesecloth. Brush with oil. Bake at 325° for 1 hour, basting occasionally. Remove cheesecloth; bake an additional 2 1/2 hours or until drumsticks are easy to move. Baste occasionally with pan drippings.
Remove skewers. Transfer turkey to serving platter. Let stand at least 15 minutes before carving. Serve stuffing from turkey cavity or transfer to a serving bowl.