Preheat oven to 400 degrees F.
Rub the entire pork roast down with oil.
Mix the salt, pepper, garlic powder, and onion powder
Sprinkle entire pork loin down with the seasoning mix.
Place pork in roasting pan fat side up.
Cook for 10 minutes.
Lower heat to 350 degrees F and cook for 15 minutes per pound until the internal temperature reads 145 degrees F. Test the temperature as it gets close to time as some roasts cook quicker than others.
Remove pan from oven, and put a piece of foil loosely on top of the roast. Let meat rest for 10 minutes.
If you want an extra crispy pork loin, pop your loin back in under the broiler for a couple og minutes, watching it closely to not burn it.
Transfer roast to a cutting board to slice for serving.