Remove and discard leg truss from turkey. Pull off and discard lumps of fat. Remove giblets and neck. Rinse bird inside and out; pat dry with towels.
If stuffing the turkey: Just before roasting, place turkey on work surface breast side down; lightly fill neck cavity with dressing. Bring neck skin up to cover opening. With a metal skewer, fasten neck skin to back, threading skewer in and out several times through neck and back skin. Turn turkey over and loosely pack body cavity with dressing. If turkey has tail attached, tuck tail into cavity. If there's enough skin to overlap at opening, thread a metal skewer in and out several times to close. Lightly tie ends of drumsticks loosely together with cotton string to keep them from spreading apart or leave untied to allow heat to reach thigh joints more easily. Place any leftover dressing in a baking dish. When turkey is about 30 minutes from being done, bake extra dressing, covered, in a 325° or 350° oven until hot (at least 150° in center), about 40 minutes for 8 cups.
Rub turkey skin with oil. Insert a meat thermometer straight down through the thickest part of the breast to the bone. (If using an instant-read thermometer, insert when checking temperature.)
Cook turkey until thermometer registers 160°; see below. Baste with dripping, if desired.
To roast, place turkey, breast up, on a V-shaped rack in a 12- by 17-inch roasting pan (or one that is at least 2 in. longer and wider than the bird). Roast in a 325° or 350° oven, as determined by bird size; see below.
To barbecue with charcoal, use a barbecue (20 to 22 in. wide) with a lid. Mound and ignite 40 charcoal briquets on firegrate. When coals are spotted with gray ash, in about 20 minutes, push equal portions to opposite sides of firegrate. Place a foil or metal drip pan between coals. To each mound of coals, add 5 briquets now and every 30 minutes while cooking.
To barbecue with gas, use a barbecue with indirect heat controls at least 11 in. between burners. Turn all burners to high, close lid, and heat for about 10 minutes. Adjust gas for indirect cooking (heat parallel to sides of bird and not beneath) and set a foil or metal drip pan in center (not over direct heat; if drippings flare when lid is open, add a little water to pan).
Set grill in place. Set turkey, breast up, on grill over drip pan. Cover barbecue and open vents for charcoal. If edges of turkey near gas heat begin to get too dark, slide folded strips of foil between bird and grill.
Transfer cooked turkey to a platter. If bird was stuffed, insert a thermometer into the center of the dressing. It should read at least 160° to be bacteria safe. Do not allow stuffing to sit in bird. Cut string from legs. Remove skewer closing body cavity. Scoop dressing out into a bowl. Cut through skin at neck cavity, scoop out dressing and add to bowl. If temperature was below 160°, heat dressing in a microwave oven at full power (100%), mixing often to distribute heat evenly until it is 160° throughout. Cover and keep dressing warm. Keep turkey warm and let stand 15 to 30 minutes.
Carve bird. If thighs are still slightly pink at the joint (typical, if oven roasted), put thighs on a microwave-safe plate in a microwave oven at full power (100%) until pink disappears, 1 to 3 minutes.
Turkey weight with giblets: 10-13 lb. Oven temp.: 350° Internal temp.: 160° Cooking time: 1 1/2 to 2 1/4 hr.
Turkey weight with giblets: 14-23 lb. Oven temp.: 325° Internal temp.: 160° Cooking time: 2 to 3 hr.
Turkey weight with giblets: 24-27 lb. Oven temp.: 325° Internal temp.: 160° Cooking time: 3 to 3 3/4 hr.
Turkey weight with giblets: 28-30 lb. Oven temp.: 325° Internal temp.: 160° Cooking time: 3 1/2 to 4 1/2 hr.
Nutritional analysis per 1/4 pound boned cooked turkey with skin, based on percentages of white and dark meat in an average bird; nutritional analysis does not include dressing.