Why my ML55 make tapping noise at drivebelt in pace with rev later ok when drive on 2001 Mercedes-Benz ML55 AMG

Tapping noise only when engine is cold, once warmed up and driven it subsides and disappear after few minutes.

Asked by for the 2001 Mercedes-Benz ML55 AMG
poss belt tensioner or idler assm
I checked the belt, felt tight.
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1 more answer , 1 more comment
After your vehicle sits overnight or for any extended period of time, the oil settles down into the oil pan at the bottom of the engine. When you first start it, there is residual lubrication on the top end internal parts but the oil pump has not pushed the motor oil up into the lifters, pistons, and valves. Therefore, you hear the tapping sound that then goes away once those parts are fully lubricated. We would have to take a look and listen to see if there is a need to perform any repairs. In the meantime, have a fully synthetic oil put in next time you have an oil change then listen to see it there is an improvement.
I have booked for a service with Mercedes, the earliest is next week, meanwhile is it ok to drive allowing for longer warm up?
Thanks lot for your advise.