Cold Start Knock (VVTi?

I have a Lexus GS 300 (model year 2003). When starting in the morning (particularly cold mornings), there is a loud knock when I turn the car on. It only has 5,800 miles and they are saying something about a VVTi System. Any thoughts out there. They say that they are replacing the part (or parts) and that there should be no resultant damage to the vehicle. Comments welcomed and appreciated. In addition, when driving a rattling in the radio/dash area. Please help!

Your cold start problem has nothing to with the Vvt-i. What weight oil do you use?

Jeff