FWIW
Here in the South, extreme noise from the valvetrain is PREVELENT more in August than other months...
I kept having friends bike making a clatter when we got stuck in traffic Jul/Aug/Sept
We started experimenting....
#1 rocker lockers work. at lowering valvetrain noise... PERIOD
#2 Full synthetic 50w, full synthetic 60w AND 20w-60 oils are all QUIETER when your motor is heat soaked in Atlanta, Memphis, Birmingham traffic during our sweltering months.
#3 I have not seen ill effects from running straight 50w or 20w-60 HERE! Of course I don't ride below 29* either! AND it is rarely below 40* here in the dirty south anyway...
#4 if you are running a fast rising, fast falling high lift cam IE Woods TW9, 408 etc YOU BETTER LIKE VALVETRAIN NOISE! It will happen.... Nature of the beast