Ask Smithy Xtra Oil use in 07 Commodore

Our 2007 Commodore SS has started to use oil. Holden did an oil consumption test said it was not a problem, but we struggle to accept that given that after just 16,649 km it?s using 2.5 litres of oil. We only discovered the oil use because we ran over the service interval and the light came on. It made us wonder how many other 6.0-litre Commodores are doing the same without the owners knowing about it. What can we do about it?