We report updated results in the search for B_s flavor
oscillations performed at CDF II.  We analyze a dataset of approximately 355
pb-1 from proton-antiproton collisions at a center-of-mass energy of 1.96
TeV collected in 2002-2004 with the CDF II detector at the Tevatron
Collider.  Samples of both fully reconstructed B_s --> D_s(3) pi+, and
partially reconstructed, B_s --> D_s lX, decays have been studied.  A
combination of opposite side tagging algorithms has been used to determine
the flavor of the B_s mesons at production time.  Information about the
oscillation frequency of the system, Delta M_s, is obtained by performing an
amplitude scan of the data, from which an exclusion limit: Delta M_s >
8.6ps-1 (@ 95% C.L.).