There isn’t a reliable single ISO to recommend for 10+ year old film. The correct rating depends heavily on how the film was stored over that time. If the storage history is unknown, the only dependable approach is to test it.

A practical method is to load a short test roll and shoot the same subject at a few exposure indexes, such as box speed and one or two slower settings, then process and compare the results. Older color negative film often benefits from extra exposure, but how much varies too much to answer accurately without testing.

So: don’t assume 200 or 400 ASA is “right” just because the film is old—run a test first, especially if the storage conditions are unknown.