I have never brined a turkey. I usually buy frozen ones, and usually I have to assume, without remembering now, that they are injected. It's bad enough their breasts are all puffed up that they can barely stand up straight. It's a wonder they dont' catch scoliosis and develop weak knees. I have to think that was not always the case. Those worthless little Plastic Pop Ups When Done thingies have been inserted in frozen birds for a long time. So they could have been injected for a long time as well. This is how I do it. After they are prepared and / or stuffed, I cover the turkey with cheesecloth or my oldest thinnest (clean) dish towel, and then pour melted fat on it. I used to use Crisco before they converted it to transfat free and ruined it. Today, if I had to, I would use peanut oil, since that is pretty much what is in the pantry. I don't think I would use olive oiil, but I am not sure why. I wonder if Lard would work. Anyway, I Baste throughout and tent if it starts to get too brown. Start with a 450 degree oven and immediately Lower oven to 325. Use thermomenter probe to check for doneness.
If I ever get a fresh farm raised turkey with no added chemicals I would use Alton Brown's brine recipe. I do not make our holiday birds. My Bro in Law at thanksgiving, and Sis in laws at Christmas always turn out good/ great / Respectable Turkeys. I am more apt to grill turkeys on a Weber Charcoaler in the summer, similiar minus the cheesecloth. and add herbs / onions/ cut up apples/ orange whatever in the cavity. Oh, and I make gravy from the drippings caught in a pan that sits alongside the coals and which also works to keep the coals separate, so it is as much indirect heat as those big turkeys allow on a Weber.
I get so jealous of Canadian Thanksgiving in October. It's like a being a kid who can't wait until Santa. Now, it's Only 10 more days til Thanksgiving. I can wait. Barely. I love turkey.