After a good old fashioned canning out on the back roads I got home and there was a light smoke haze coming from right hand side of the engine.
Oil was not poring out or any thing but there were bubbles coming out of the thread, you can see two small bubbles in the picture.
Car runs OK... what causes this?

 

Certain nuts are on studs that go through oilways. This one must be, and oil is migrating up the stud threads. leave it alone and the oil will bake and seal the threads. A little known fact on the famous venerable Jaguar 6 cylinder XK engine was that dome cylinder head nuts were fitted to stop this exact phenomenon.
The car will be delighted to have been driven hard, keep it up!

 

Agreed.

 

Sorry to disagree with others but the only oil pathways for the head are the feed via hardline at rear of head and drain back path at outside rear corner of each head and of course the timing cover.
I think it more likely oil has somehow found it's way into the threads of that outside stud and is being driven out by the heat.
Either way l don't see it being a big deal. Those outside studs are anchored in solid aluminium away from any oil or water contact.

 

Ok - thanks.
I was thinking .... not good. Even to the point I should not have driven it so hard.
I shorted the kick down switch on the throttle body to see how it would go. except for not changing up when going slow the dam thing took off.
Great fun I say! Might be cool to have this on a switch, like sport mode.