I have had the car for 2 months now and roughly 4 times when I started it it sounded like there was no oil,making a knocking sound which lasts about 2 seconds.Just the other day I turnt the key and the engine started but it sounded like the starter keep cycling for about 2-3 seconds....was just wondering if anybody else has had this issue....I called GMC service in my area and they said it would be hard to duplicate the situation if it happened that rarely.....to wait and see if it got worse or happened more frequently.