Remove roast from refrigerator 2½ to 4 hours before cooking, the longer time for the largest roast. If you don't let the roast come to room temperature, it will take longer to cook.
Preheat oven to 450° F.
Pat the roast dry with a towel or napkin.
Smear the cut ends of the roast with the oil or butter.
Liberally apply salt and pepper to the cut ends and the fat side.
Place the roast (ribs down) on the rack in the roasting pan.
Sear the rib roast for 15 minutes at the higher oven temperature (450° F ), and then turn the oven to the lower temperature (325 °F) for the rest of the cooking time.
Every ½ hour, baste the cut ends of the roast with the fat accumulated in the roast pan.
About ½ hour before the estimated end of the roasting time, begin checking the internal temperature. Cook until rib roast reaches an internal temperature of 120° F.
Remove from oven, cover with aluminum foil, and let sit approximately 20 to 30 minutes. Remember, the roast will continue to cook as it sets. The temperature will rise to 125°F to 130°F internal temperature (medium rare).
Note: To hold cooked roast until serving time, immediately turn off oven and leave door ajar after removing roast. Let roast sit 15 minutes on counter and then return roast to the oven, door closed, for up to an hour or even 2 hours for the biggest roasts. Check the temperature every 15 minutes. It will rise approximately 10°F at first, then gradually subside.Note on Meat Temperatures: What constitutes rare and medium-rare cooked meat? To satisfy government home economists, the beef council says rare beef means an internal temperature of 140°F. Well, that is ok if you like well-done and dry meat. If you like moist, rosy meat (like I do), rare begins at 120°F and starts to become medium rare at 125°F or 130°F degrees. To cook your meat properly, you must purchase and use a good meat thermometer.This chart is only a guide. You must rely on an accurate meat thermometer and start taking temperatures an hour before the end of the estimated roast time.