To use an oven bag and best alternative to butter?

A bag basically poaches the turkey in its own juices. If you want crispy skin, therefore, don't use one. Butter under the skin is not at all necessary. Drizzle olive oil over it, with your hands rub it all over the bird, followed by salt and pepper. The secret to a tender, moist turkey is not to over bake it. Remove it from the oven when a thermometer reads 160 at the densest part of the thigh. Transfer it to a serving platter. Cover it with foil and a double-folded bath towel so that the water roving around outside the cell walls can re-inflate them once the stress of baking is done. Let it rest as such for a good 20 minutes while you create gravy from the pan juices. Enjoy your Thanksgiving.

Duck fat is fantastic! I slather an herb, citrus, spice compound duck fat under the skin of my turkey before cooking it.

Olive oil would be a good substitute for butter I've never used a bag but friends do and their turkey is always tender and tasty/