OFHG or VCG? Pics attached

[Sanfordev]

This past week my tensioner started chirping on my 2013 135i with N55. I replaced the serpentine belt and that didn't solve it, so I replaced the tensioner and both idle pulleys.

When I had everything off I could see a thin buildup on the bottom of the alternator, and on the top of the pulley that's directly under the alternator (Deflection pulley?)

I degreased it all and got it shiny again, but question is - how do I locate the source to repair? Any tips, or is this obvious from from another member having the same experience?

[NorthernDancer]

Oil Filter Housing Gasket most likely. Look up repair on youtube. Its a little more difficult on N54 and N55 than N52.

[juld0zer]

Yep.
Rocker cover gaskets usually pool on the exhaust side due to the slope of the engine and will cause lots of smoke when it drips onto the exhaust

[Converted1]

Yours looks slightly worse than my 09 N54 with 45K. No chirping on mine but I have the OFHG parts and I’m eager to get it done. Not my DD and waiting for a few warmer days.