Every 12,500 miles...
I don't have the manual infront of me but I think Maserati service intervals after the 6,000 mile check up, are every 12,500 miles not including additional oil changes that should be done between services.
Most services include fliters, fluid flushes and oil changes. At 30 K, I think they replace plugs. Time is also a factor.
If you get a 30K or 50K service, please goto the service thread on this board and post your invoice numbers. Thanks.
CM