General comment on the noise frequency / synch with wheel rotation - I think it makes sense for something to be synched with wheel rotation (or some other rotating thing like a driveshaft, pulley, fan, gear), or NOT. Synched or not synched. Not both.

I can't think of any single issue that would sometimes be synched with wheel rotation and then sometimes still be present but not synched. Sure I can believe it goes away completely intermittently. But to switch into an un-synched mode would be pretty weird. Maybe it's still synched but missing beats for some reason?

So I'd put more diagnosis testing into resolving that. Synched vs. not will do a lot to narrow down what the problem could be.

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2001 X5 3.0i, 203k miles, AT, owned since 2014