If searing the pork loin beforehand, add olive oil to a large pan and heat on medium-high heat.
Season the pork with salt and pepper.
Sear the pork on all sides until golden brown. Remove from pan and place in the slow cooker.
Pour root beer over the pork and set the slow cooker on low heat.
After 4-5 hours, check on the pork. If pork pulls apart easily, begin to shred it apart.
After 2 hours, add the bottle of barbecue sauce and season with salt and pepper. Stir to combine.
Shred the pork into smaller pieces, if desired, and continue slow cooking for another hour.
Serve pulled pork on hamburger buns with extra barbecue sauce.