You're sure it doesn't have a bluish tint? Because that would indicate oil burning. And it may not do it at idle but under a heavy hit of throttle and load. Like passing a car or launching.
No coolant loss was found I checked for that this past weekend
and number 8 has to do with the ring land breaking, not the valves.
It's both. The ring lands break due to detonation, and the exhaust valve guides wear due to poor coolant flow at the back of the driver's side cylinder head. This is the remedy:
http://www.modularmotorsportsracing.com/cart/index.php?main_page=product_info&products_id=555
It doesn't work. Its already been tried by several including myself. Temps are the same before and after mod. My coyote is full of MMR stuff that i built.
..... but what do i know.
The Gen 2 used the Roadrunner heads from the Boss 302 so I wonder if they'd been mildly redesigned to improve coolant flow around the exhaust valves.