Commodore oil consumption

I too have a 2010 Commodore 3.0-litre SIDI with oil consumption issues. I have completed the first oil consumption test with my dealership and it used 0.4 litres in around 1600 km (2.5 litres per 10,000 km) and was told this was within spec? My dealership asked if I wanted to try the manual specified 10w30 instead of the 10w40 they'd been using, to which I obviously agreed. They asked me to make a specific log, including loading, usage and fuel used, and to come back in 3000-5000 km for another consumption test. I just want to know my rights as a careful first time new car owner, and whether or not Australian consumer protection can add leverage to the situation. I understand that Holden needs info for diagnostics/future reference, but I want this problem resolved asap. I bought a new car to avoid problems such as the one I'm experiencing, and I'm starting to feel like I've wasted a whole lot of money. Any useful advice would be greatly appreciated.