The response of a global ocean general circulation model (OGCM) to different surface heat and freshwater fluxes is examined. The aim is to determine the most appropriate way to spin up an OGCM prior to coupling it with an atmospheric GCM. Attention is focused on surface boundary conditions for salinity since other studies suggest that so-called “mixed” boundary conditions (i.e., a restoring condition on sea surface temperature and flux condition on sea surface salinity) can yield multiple equilibrium states in ocean models. Under the influence of restoring surface boundary conditions, the rate of overturning in the model North Atlantic is in good agreement with observed estimates. Under the influence of mixed surface boundary conditions, however, the rate of deep-water formation in the model North Atlantic is far in excess of the observed estimates. If the equilibrium solution obtained under restoring boundary conditions is subjected to an equivalent set of mixed boundary conditions, the presence of systematic errors in the model causes the model equilibrium state to change. The transition between equilibrium states is smooth and no persistent thermohaline oscillations are excited, which disagrees with the findings of other investigators. Persistent oscillations could only be excited in the model if the realistic ocean bathymetry was replaced by a flat bottom everywhere, in which case an oscillation with a 10-year period was excited in the North Atlantic sector of the Arctic Ocean.