Vibration under my 02 Impala?

Has anyone experienced any noisy vibration during a morning start. It also happens when the car has been sitting for awhile. (Going to the store and to work). The vibration sounds like soda cans rattling under the car between the driver and passenger side. It stops when the car is warmed up. I have chaged the oil recently using 10w30. It has transmission fluid. Anyone have any idea what's going on?

It's the oil pump. Mine does the same thing, I was told it was because the pump was hydraulic and it takes a few minutes for it to circulate or something. I called chevy and they say it's normal. I have even looked at brand new ones and they do it too. Nothing to worry about.

Mike

bermis519
Thank you!
I am happy to know now that it is normal.

bermis519
Thank you!
I am happy to know now that it is normal.

I have found out that my catalytic converter is clogged. That was the rattling under my car between the driver and passenger side. I needs to be replace.