In a stockpot or clean plastic bucket, combine 2 gallons cold water and  sea salt. Remove all giblets and other parts from the turkey cavities; discard or reserve for another use. Place turkey in the salt water brine and refrigerate for 8 to 12 hours. Remove turkey from the salted water; rinse well inside and out with cold water for several minutes. Pat dry, including cavities, with paper towels. Preheat oven to 425ºF. Slide a wooden spoon between skin and turkey breast to separate (see tips). Brush the Wildtree Roasted Garlic Grapeseed Oil between the skin and turkey breast meat. Melt butter in a small saucepan and add Wildtree Herb Grilling Marinade. Mix thoroughly Stuff turkey and place breast side up in a shallow roasting pan. Add ¼ cup water and quartered onions to roasting pan.  Roast turkey in the oven for 30 minutes. Reduce temperature to 325ºF and baste with the Herb Grilling mixture. Continue to baste every 30 minutes until turkey is done.  The turkey is done when a meat thermometer inserted in the thickest part of the thigh registers 170 to 175 degrees. Remove turkey from oven and cover with heavy-duty foil. Let stand for 30 minutes before serving.