Drizzle half of oil over the top of the pork loin. Sprinkle half of ranch dressing mix over the top of the pork loin. Rub ranch dressing mix and oil so the pork loin are covered on top.
Flip pork loin over. Repeat step number 2 with the remaining oil and ranch dressing mix.
Let pork loin rest for 15 minutes.
Place on grill and grill 6-8 minutes on each side.
Preheat grill to 350 degrees. Place tenderloins on grill. Grill for 30 minutes or until internal temperature reaches 145 degrees. Rotate the tenderloins every 10 minutes and baste with remaining marinade.
Remove from grill and cover with foil. Let rest for 10 minutes before slicing.