Thanks for the reply guys. We're thinking along the same lines. First thing I did was check the oil level and topped it off. I was about a pint low. No change.
I think I'll change the oil and filter as they are about due anyway, and see if that cures it. If memory serves me right, I ran 15W50 all last year with no issues, so that may do the trick.
As far as wearing out I guess that is always a possibility. Its got ~123K on the original head. But . . . I've been using Mobil 1 with 3-4K since about 65K, and the prior owners did similar according the the records, so I thinking it should go a bit further before its worn out. And yes, cam chain tensioner has been changed
