I haven't yet read an owner's manual the recommends changing (flushing) power steering fluid.... but then again most of the US auto manufacturers don't address the issue of changing brake fluid either! My MB owners manual doesn't recommend it. They probably don't recommend it because it's a messy job and the system isn't designed for a clean change.

A lot of do-it-yourselfers change power steering fluid anyhow. Any contaminant wear debris in the system not caught by the filter gets flushed out with the old fluid. Plus the old fluid may be degraded.

If you do flush the power steering fluid I recommend changing the ps filter at the same time, and don't use ATF. Over the years ATF has evolved with a different additive package that may be hard on seals designed for the old fluid. Use power steering fluid. Considering it's twice as expensive, and you typically use only two quarts for a flush, it's cheap insurance.

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95 E320 Cabriolet, 169K