I don't agree with him on the oil change being the cause of the timing chain problems.  Parents have an Acadia that is a couple years old, either 08 or 09 I think with about 60,000 miles on it.  The dealer they got it from has a deal when they bought the vehicle that if you have them change the oil every 3000 and rotate the tires every 6000 they will pay for your new tires.  He has had the oil changed on schedule to make sure he is good for the tires and they still had the timing chain failure.  They just got it back and warranty did cover most of the repair but they did end up paying for some that they did not consider part of the power train.  They have a problem with their chain supplier for these engines.