[Hal H]

But Uncle Tony says its because the cam sits too high up in the block. I say uncle Tony is full of baloney.

I would agree with likely poor hardening/metallurgy being the most likely cause. Most major auto manufactures (big companies in general) farm out the production of their parts and go with the lowest bidder (frequently 3rd world country). While parts are supposed to be produced to stringent specs per the bid there is never enough quality control/verification.

Its all a race to the bottom game for next quarters profits. So long as they are not having to do too many warranty repairs they are unconcerned.

From my studies 2017+ (2017 start of full implementation) they increased the size of the needle bearings in the rollers substantially. This may or may not have helped depending on if hardening was being done correct.

Anyone know if issue has slowed down on 2017+ ???

2017 and up needle bearing size increased.
View attachment 1106499

I did a cam swap on my '16 SP - M6, so it has the non-MDS lifters -

The lifters for my Sep '15 build engine - the AA suffix lifters had the same size needle bearings as the lifters that had a Julian date ~ Aug '20 (purchased Apr '21)

and like other posts in this thread, I've stated that the needle roller bearings failing is what causes the lifter to gouge out the cam lobes. Its not the cam itself, but the roller tip dragging on the lobe, grinding it down

Old lifter on left / new lifter on right

 

[Hal H]

this is great, what would you recommend, changing the lifters as a 100 buck precautionary measure every 30k miles?

that would get very expensive - nearly $600 for a set of lifters, head gaskets, intake gaskets, intake head bolts (they're single use, torque-to-yield) and if you're paying someone to do this - the labor rate for that work, as they heads must be removed to access the lifters