Did you replace the seals as well?... they are a consumable item. Yes, the grease leakage may have been the result of substandard grease. but my first suspicion would be the seals.

A good synthetic grease that is widely available is Mobil 1 synthetic. A better one is Exxon Infinitec, but this is yet to be sold retail.

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95 E320 Cabriolet, 169K