Time periodic solutions are found for the natural convection of a Pr=0.71 fluid in a differentially heated 8x1 cavity at Ra=3.4x10 5 using a "straight" Galerkin finite element method with the Q 2 Q 1 element. Time integration is performed with an implicit second-order accurate (in time) trapezoid rule. As expected, the average values of various solution metrics were relatively insensitive to mesh refinement and time integration truncation error, although coarse meshes tend to damp out the time periodic behavior. The amplitude and frequency of the oscillation is sensitive to both mesh and time truncation errors.