Preheat the oven to 425 degrees F. Tie the legs of the turkey together with string and fold and tuck the wings under the body. Place in a roasting pan. Brush with oil and then rub with salt and herbs. Roast the turkey 20 minutes, then reduce heat 325 degrees F and roast, basting occasionally, approximately 2 1/2 hours, or until temperature reaches 180 degrees F when a thermometer is inserted into the deepest part of the thigh. Remove the turkey from the pan and rest 20 minutes before carving. To make gravy, skim fat from the pan drippings and add 3 cups of the chicken stock. Bring to boil. Mix 1/4 cup flour with 1/2 cup cold water until smooth. Whisk into stock and simmer until gravy thickens. Season to taste.