I don't want people to think I have all the answers, I don't think anyone does butt I just want to throw my opinion out there as I have worked on enough to see trends. I am just reporting what I see.

There are a few things that make me think it can't exactly be just an "oiling issue", I think if it was just an oiling issue it would be consistently one or a few particular lobes, I have seen no consistency of witch lobe is affected, most of the time it is just one single random lobe, I even try to take note of witch lifters no longer roll smooth on a piece of glass and see no particular lobe that is more susceptible. The early 5.7 and 6.1 never had this issue and at least the 5.7 in police service saw many many hours of idle time and I have never seen a bad lobe one one of the 03-08 5.7 or any 6.1 ever. They run the basically same idle oil pressure as eagle engines.

I tend to agree with what the factory seems to think the issue was, it seems they made smaller needle rollers (I suspect probably because they thought it would be more quiet) when they came out with the VVT engines, this needed a thicker roller wheel, that thicker roller wheel blocks more of the splash oil from getting into the roller wheel and lubricating the needle bearings and the fact they are smaller diameter means they just can't last as long.

Since the dealer parts guy pointed out the difference in needle bearing diameter to me I looked in my scrap bin and all the failed lifters had the small bearings as well as all the ones I have done since then, 100% had small needle bearings, others may have seen the bigger ones fail but I can't even find a single picture of a failed large bearing lifter on the internet butt there are plenty of people who claim to have seen them.

I try to buy cars and trucks with the failed lifters all the time (easy repair for me now) and the vast majority that have or supposedly have the issue are all 2009-2011, I see very few 12 or newer. I have not narrowed down the exact year they changed the lifters but 2011 definately had the small bearings and seems to be the worst year hands down and I had a 2014 ram 2500 5.7 I bought with broken springs and a local chevy dealer had already pulled off the heads for the previous owner and told him it needed an engine (it didn't) and it had the large bearings in the lifters. I put on new valve springs, reused the lifters and slapped the heads back on and 30,000 miles later is still running great.

I did have a 2014 6.4 BGE engine I bought with a flat cam one time, I honestly don't know what lifters came out of it, pulled em all out and threw em away before I knew to look for the difference. IF it had the same lifters as a 5.7 and IF it was small bearings that would indicate the change happened in 2014 model year but that is pure speculation on my part. It was basically a short block and I suppose it is even possible someone threw an old junk 5.7 cam and lifters in there, I put all SRT rotating assembly and eagle heads on it and ran it in my 2011 1500 (another I bought with a bad cam).

Like I have said before I do not remember ever seeing a MDS lifter fail, none of the cams still laying around here have a bad MDS lobe. If you think about it, any time it is operating in 4cyl mode there is basically no load on the lifter wheel so it should theoretically anyhow experience longer life. I have seen one bad MDS solenoid, otherwise the system seems flawless to me.