Holden Astra 2007: Very noisy engine

On the basis of what you have described here it doesn’t sound as though the car is unsafe, and I wouldn’t be reluctant to drive it. I can, of course, understand that you feel frustrated at not being able to get a satisfactory explanation of the cause of the noise. I would suggest that you go back to the dealer and ask for a meeting with the service manager to discuss your concerns. Have the manager talk you through what they have found wrong with your car and what they have done to fix it, and ask them to justify to your satisfaction that it is indeed fixed. If you’re still not satisfied ask them to have a Holden factory technician assess the noise and give you a report on it. Further to that you could have an independent mechanic assess it for you.