Thanks, tandkj, for the advice. For obvious reasons, I am trying to avoid buying a large tube for a small job and having the rest go bad. If your technique preserves the material in the tube for a reasonable amount of time, then Dicor appears to be a viable option.
As stated previously, I am assuming the original caulk was Dicor. Whatever it was, it seems to be retaining its color (white) without darkening under normal use conditions. In your experience, is this consistent with Dicor applications? Or am I making the wrong assumption?