I recently bought this car and knew about all the oil leaking problems this car could potentially have. Therefore, I checked the fluids every other day just to see if and when the car is leaking. Well one morning a couple weeks back, I started my car and it made the worst knocking noise ever. After it ran for a minute it went to a dull knock in the lower end of the motor. I checked the oil, and it was still clean and at the right level. Well, now every time I start the car after it sits for a few hours, it knocks loud and then progresses to a steady knock that doesn't increase with RPM speed. I believe it is signs of early bearing failure on one of the rods. I am not for sure but very disappointed in the GM brand. I have had a few GM cars, and will never buy another as they all have had issues severe enough to prevent me from driving them.