Intermittent Sound from oil cooler / alternator area. 3.0L X6

[konstanting334]

In the video, after the 15th second you can hear it. It's intermittent and not constant. Once you raise the rpm, the sound is gone. But mostly comes when in drive (rpm are at its lowest).

Changed oil filter and oil, but still nothing. Before it would come on a few seconds a day, now it's almost constant when at low idle.