Oil on exhaust mainfold stud / nut

Hi All,

I would appreciate if I can get some feedback on the following matter.

I have a 91 Ford Maverick GQ 4.2l petrol carby. I believe this is a 91 Nissan Patrol replica.
I noticed a very minor oil track at the bottom of the bell-housing.
To the best of my knowledge, I believe I have tracked the origin.
It seems to be coming from the exhaust manifold, cylinder 6, bottom bolt.

Please see attached photo which shows the oily nut (highlighted in the red circle).
Photo is taken from below the engine bay.

I will really appreciate if someone can guide as to what could be causing oil to be appearing on this stud?
Also what is is the nut highlighted in the green circle?

Attachment 88189

Many thanks

Welcome to the forum. My guess is that much oil would be external. Have a look a bit higher up and check the rocker cover gasket, which is a common spot to fail. Sometimes torqueing the screws a bit seals it. But the rubber goes brittle and usually cracks if you just tighten it up.

Thank you mudnut for the feedback which is on the right track.

I felt the area at the back of the rocker cover and could feel oil.
Hence very likely that the oil is seeping via breakage in the rocker cover gasket.
I will remove the rocker cover and investigate.

Any idea what the bolt is highlighted in the green circle?

Whatever that is, it shouldn't be loose. Hopefully someone that owns a TB42 can tell you.