Generation noisy

You're right to be concerned as there are lots of reports of problems with the Gen III engine. You're also right they can use oil at an alarming rate, and they can have a piston rattle. Holden has rebuilt lots of them under warranty, so I would ask the seller about any work that has been done on the engine. Ask for proof positive that work has been done if they say it has. Ask also for any records of oil consumption they might have kept. It's impossible to tell if an engine is using oil simply by looking at it, so you have to try to get as much info out of the owner as possible, and hope they're telling the truth. Check the service book for anything that might say it's been in for extra servicing, or had additional oil added. As for the noise, listen carefully for a light metallic rattle as you blip the throttle. There's no need to rev it hard, simply blip the throttle and you should be able to hear it if it does rattle. Keep it in the back of your mind that there are plenty of cars out there, so if you have any doubts about the car you're considering, walk away.