vtail wrote on 12/31/69 at 16:00:10:That's the thing, it did not turn and was still in the same spot. I torqued it again and the nut turned 60 degrees. So I'm getting suspisious
I'm thinking that yours is an exception (to a rule that I can't explain). 1/6 of a turn on a bolt isn't that much. The head is aluminum, so maybe the nut is seating into it.
You said that you did your own initial service, right? (meaning it has been done). The head studs are not simple mild steel. They should not stretch and the threads should be harder than the nut. Maybe you can remove the nut and check the threads on the stud or nut next time it is loose.
The nut usually leaks a little anyway, which is why I told you about my experimental fix. I think it's in the design of the gasket. No leaks on mine, yet. We'll see how it goes.