Holden Commodore 2002: What is the service interval?

There is no Holden recommendation, as far as the company is concerned the transmission has been filled for life in the factory and needs no further servicing. The trade has a different view, however, and generally recommends an oil change service every year, and a major service, which would flush the transmission every two years. There’s no hard and fast rule, it comes down to common sense. In your case, at least get the oil and filter changed.