I've deep fried a few turkeys, without brining. They came out nice and juicy. They were frozen turkeys that I thawed before frying. I didn't check to see if they had been "pre-brined" by the packager, so I suppose that's always a possibility.
Once the oil was up to temp, it only less than an hour to cook a 15lb bird. You know you're close to finishing, when the turkey begins to "bob" or float in the oil. At this point I remove the bird and test internal temps in several places for doneness. If you leave in much longer, you'll run the risk of drying it out, and letting it get real oily. The skin comes out nice and crispy. I then let it rest, BREAST SIDE DOWN, so any juices in the dark meat can flow into the white meat.
I use canola oil and use about 5 gallons of the stuff. I have a Brinkmann rig, with a 42quart pot with a metal basket insert. You can use peanut oil, and re-use it, but the canola works fine, it's significanlty cheaper for a one time use, and I don't have to worry about filtering/storing used peanut oil for additional fryings.
I know lots of folke like to inject flavorings. I like my turkey to taste like turkey, so I don't inject anything. I do rub it with my favorite rub just before putting it in to cook.
Sorry for the length of this. I hope the info helps.
