Fresh oil sand slurries were prepared and tested in a 100 mm pipeline loop at 37 degrees C to evaluate the effects of average flow velocity, slurry air content and air injection method (bulk or continuous) on slurry conditioning, i.e., the evolution of the in-pipe processes that promote gravity separation of bitumen-air aggregates from the remainder of the slurry. The potential separability of the bitumen in the slurry was evaluated using a slurry Conditioning Index (CI). When no air was injected into the slurry, the slurry Cl was low (<= 0.1), indicating very poor conditioning. An increase in flow velocity from 2 m/s to 4 m/s and injection of 5% air (by volume) dramatically improved the slurry Cl, to -0.6. The improved slurry conditioning observed at the higher velocity is explained by the increased force of fluid turbulence experienced by the particles and the greatly enhanced bitumen-air contact.