The owner'* manual recommends that the supercharger oil level be checked every 30,000 miles. I check mine every 10,000. In addition, some people change out the oil every 50,000 miles. I changed mine at the 120,000 mile mark.
It'* longevity is a function of how well it is maintained, and how agressive your driving style is. In addition, the earlier superchargers (92-95) used to leak supercharger oil, adding to their demise.