Concerned that this issue may have been prevented if using a basic oil change policy(every 3000) instead of using GM oil change indicator in which we changed oil every 5000-7000 miles. Should GM change it's policy on oil changes or do more studies on the oil change indicator. This vehicle is almost 3 years old and only has 56,000 miles, it should not have such a big repair bill. Worried about more problems to come.

There has been a persistent noise when sitting at idle that appears to be coming from the tranny hump or from somewhere behind the firewall. It sounds like someone is lightly tapping one knuckle against the sheet metal about two times per second. Can't hear the noise over the engine and road noise once you accelerate to speed.