Preheat oven to 450°F.
Pat the roast dry completely.
Mix oil, butter, and minced garlic.
Add rosemary, thyme, salt, and pepper.
Rub mixture all over the prime rib.
Place roast fat side up on rack.
Roast for 20 minutes at high heat.
Reduce temperature to 325°F.
Continue roasting for 1.5–2 hours.
Check internal temperature (135°F for medium-rare).
Remove roast and tent with foil.
Let rest for 20 minutes before slicing.
Slice and serve warm with sides.