Damn, thanks. Thinking then that the tick issue may have something to do with the cam, lifter, pushrod geometry that for some reason, in some engines, requires a specific lubrication chemistry to mitigate. Why else would so many folks with the tick have it significantly reduced or even eliminated by simply changing the engine oil to Redline 5w-30 or an even more viscous Redline variant.
Brings to mind the issues VW had with their 2004 to 2007 PD diesel 4-cylinders. In those motors (I had the misfortune to own one), the overhead cam not only depressed the valve spring buckets, but also depressed another set of buckets, with much thinner lobes, requiring much more force than depressing valve springs, which drove the in-head fuel injection pump. An incredible number of early cam failures associated with the fuel pump cam lobes on those motors, as the supplied lubrication flow, and the additives of the specified oil couldn't protect for the loads routinely seen by those parts.
I began using Schaeffers 5w-40 synthetic diesel oil early in mine, and I have to believe that that oils relatively high moly content saved that motor from an early demise.
VW never did admit there was an issue with those engines, but quickly abandoned that design in 2008. I could go on and on about VW, but thats not relevant here.
What I believe after reading all the issues with the hemi tick and what has and has not mitigated it, is that the hemi really needs a more viscous oil than the CAFE driven 5w-20, and also an oil with relatively high amounts of moly. (~1000ppm of zddp wouldn't hurt either, but we'll never see that from a modern API spec oil)
The percentage of hemi's that experience the tick is unknown, but does not appear to be statistically significant over the total number of those motors on the road. Perhaps it's a manufacturing tolerance issue, and slight variances in machining setup as the engines are being manufactured determines if a hemi will experience a tick or not. The number of ticking engines being reported back to the OEM may be so small, in the profit & loss world of the auto maker, no action is warranted.
Although no definitive fix has been devised, thru the good work of many on this forum, the use of a more viscous oil than the OEM spec 5w-20, and either one with decent levels of moly, or moly added with an oil supplement, appear to at least mitigate ticking engines, and ought to certainly work to prevent the tick in engines that so far are quiet.
Apologize for the long-ish post, just thinking out loud.
