Some wear comes from the OCI.
There is an older Ford/Connoco SAE study that shows correlation to slightly elevated wear occuring right after an OCI. IOW - change you oil too often and you can actually be accelerating wear. Now, I don't think that 3k mile OCIs are the cause of this, but it's a good read (been many years since I've looked it over).
This all becomes a question of ROI. What do you "need" out of your investment? How long should it last? What wear rates will get you there?
Let's look at two examples:
(Note - this is not a diesel, but it's a good example of high mileage and frequent OCIs):
http://www.knfilters.com/news/news.aspx?id=157
This is but one of many vehicles that made it to one-million miles! (Google is your friend - you can read about many of them).
Note that while he subscribed to the concept of saving money with a reusable air filter, he didn't seem to embrace the syn/bypass concept, and eschewed it for frequent OCIs.
How "good" was his engine after a million miles? I cannot tell you.
How much further could that vehicle have gone if using syn/bypass? Don't know.
How much money could he have saved if he used syn/bypass? Probably a lot more.
But ... it made it 1,000,000 miles with not a drop of synthetic in sight, nor any premium oil filters. Just good old store shelf stuff at the autoparts store. And this is NOT the only story as such; there are many vehicles that have succeeded in this approach.
OTOH - there's me. I don't accumlate many annaul miles on my 2006 Dmax; probably average about 6-7k miles a year total. If we accept a reasonable lifespan of 300,000 miles as a minimum with proper maintenance, that would take me about 40 years to get to that point. My truck would either:
1) rot from the road salt in the midwest
2) die from a wreck
3) get traded or handed down to another out of sheer boredom.
Here is the UOA from the Cummins I referred to earlier:
http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=2179591&page=1
approaching 20k mile OCIs with dino oil and normal filter! Now, you may not be able to get there, but you won't know until you try. But - we cannot argue that he certainly isn't getting his ROI, can we? And yet his wear is very reasonable.
Point it this ...
Until you lay out your plan in a logical fassion, there is no sense in worrying about what oil is "best", etc.
Allow me to quote from our sponsor, Blackstone:
What's the best oil to use?
Ah, the million dollar question. We are an independent lab, so we don't make recommendations. It has been our experience that oil is oil, and either petroleum or synthetic-based oil will work well for just about any engine.
Come on, you're holding out on me. I should use synthetic, right?
Buddy, you should use whatever you want. Synthetic oil won't guarantee a longer engine life any more than my eating organic food will guarantee I'll live until I'm 90. We here at Blackstone generally use regular petroleum-based oil because honestly, it works just as well for us.
Now, that quote is admittedly a bit vague, but it drives a point home. You don't "need" premium products to make equipment last. What you "need" is a plan that sustains a desirable level of wear to a point that would satisfactorily maintain the equipment to a point that you expect to own it. What they are telling us is that synthetics don't make equipment last longer; synthetics last longer in service.
Will you ever own the equipment long enough to make a premium product plan pay off? Can you make the ROI pay out?
Some would argue that perhaps the 1-million mile engine might be "better" after all those miles, but at that point, I dare you to find someone who actually cares enough to give you money for it. At that mileage, you're not going to get more "trade in money" for using Amsoil ... No dealer EVER gives you more money for using synthetics when you trade in a truck. After a million miles, the only worth on a typical vehicle is sheer astonishment of the fact that it runs.
Are YOU going to run a million miles?
Wear rates and wear totals are very important to setting condemnation levels for the lubes. But, OEMs have ZERO interest in that approach. Their warranty period has long since expired. They only care about their risk, not yours. Yes, past that, you're on your own.
But we can still use those levels from the CA study to set reasonable limits and "fine tune" our approach.
For most people here, UOAs are a toy. They try to get the lowest ppm counts, rather than try to find the longest run on the lube.
The key to understand is that lifespan of the equipment and lifespan of the lubes are not mutually assured. You much manage BOTH to an end that satisfies your "needs". IOW - you don't "need" premium products to get a long life span out of your equipment; you need a good maintenance plan.
That plan can be either:
1) frequent OCIs with normal fluids and filters
2) extended OCIs with premium fluids and filters
Either one, when managed well, will get you there.
Depending upon your annual mileage and OCI plan, one or the other will cost less, but still achieve the same end result (remember the ball game example? The RESULTS are what matters most; not the inputs).
The goal should be low wear rates, managed wear totals, and the least cost product that can provide those two.
Your Cummins engine is likely to outlast your truck and/or your desire to own it. Just take good care of it and don't worry about it. Just change oil frequently, or use premium products. Differenet means to the same end.
As for your "wants", that's an emotional ride you'll have to take on your own.
I do think you're starting to understand. I think you're starting to see the "truth" from Jessup.
There is not one single perfect answer; there are many good answers that, when managed well, will provide you with what you "need".
