[BMWCowboy]

Any BMW geniuses happen to know what it is I'm hearing. Sounds like it's coming from the front end, driver side...a pulley, perhaps? This assumption is only based on trying to localize the sound by ear AND the old "long screwdriver to the ear" test... I seem to hear the sound more so when I make contact with the alternator and idler pulley than anywhere else on the engine. I'm don't think I hear it when the screwdriver hits anywhere else on the engine itself.

https://www.youtube.com/shorts/_Fi4pbpH_18

For clarity, the intermittent "rubbing/grinding" sound is what I'm referring to, not the constant regular ticking of the engine.

For what it's worth, this is a 2012 535i N55, with 155k on the clock. Last service was oil change with Liquid Moly 5w40 and I popped in some new stock plugs (BMW ZR5TPP33 Spark Plug - Bosch 0242145515), about 130 miles ago. Do not recall hearing this sound after the oil change. I'm guessing this symptom started today.

Does anyone happen to be able to share some not-bad news regarding what this sound could be and where I should start the deeper investigation?

[Conserve]

I would look into drive belt assembly more closely. I would have some to rev the engine and absorb any change in the noise. When was last time drive belt and associated components were replaced given you have 155K on the car?