You can put in the more free flowing GN4 (10w30) and see if that alleviates the perceived tick you are hearing. As I mentioned earlier, I'm running 5w40 Rotella, not 15w40.
I meant to say that you should stay with a synthetic since that oil's properties exceed dino oil for longevity; such as shear life and contaminant suspension.
21 years Army (retired)
...been everywhere, seen everything, done almost everything.
IBA 80537
The guy who invented the first wheel was an idiot -
the guy who invented the second one... he was the genius!
http://theringfinders.com/blog/Larry.Royal/