Crex 39 better primary oil is always a better idea . Prob. not a coincidence . Syn 3 will work ok but it is noisier.

 

That gravel sound is whats called "predetination". See this: (https://www.hdforums.com/forum/softa...verheated.html) It's the top of your heads being distoyed. Most likely the rear as it is hotter. XIED's was my fix.