I understand your concern; nice new truck at a premium price now days. Certainly want to protect it as an investment.
The thing is, there's not any data that supports a minor grade-shift being anything terrible in terms of wear control. And that is the PRIMARY JOB of a lubricant; to reduce wear. Sure, it "cools" surfaces, and it "cleans" surfaces. But it's number one job is holding wear down as best it can. In fact, vis in and of itself has zero bearing on cooling and cleaning, so the ONLY thing vis may or may not affect is wear. And there are only two ways to know if wear is in check, or out of control ...
1) complete engine teardown to measure all clearances and do visual inspections of surfaces (an ungodly expense in time and money no one in their right might is going to do every 10k miles or so)
2) run some UOAs and take the wear metals as implications as to the overall influence the oil is imparting to wear control; UOAs won't show you all wear, but you can take intelligent inferences from the wear that you do see.
So unless your wear rates are in poor shape, the vis shift is kinda moot. If you had very good wear from a 20 grade, would you automatically make it "better" using a 30 grade? Probably not. If you used a 30 grade and got good wear trends, would it degrade into the abyss by using a 20 grade? Again, probably not. And the ONLY way you'll now (in a practical and inexpensive manner) is to track UOA wear data.
The primary "inputs" to wear control are vis, FP, additives, contamination, TBN/TAN, TCB, etc ... those are all conditions which may predict a potential outcome. But the wear metals are a truthful account of what's ACTUALLY HAPPENING in the crankcase. Wear metals are "outputs" which tell you how things are occuring.
Because the truck is so new, it's totally normal to see high wear metals; residual break-in. So there's pretty much nothing to glean from early UOAs. Knowing the vis or FP isn't going to automatically tell you if something's good or bad. They will only be indications of a need to pay close attention to wear should an input go way out of whack. A minor grade shift should not be interpreted as being "way outta whack"; it's totally normal to see lubes shear, admittedly some more than others, or some sooner than others, but it's a normal phenomenon.
Though it's an older study, check out SAE 2007-01-4133. In that Conoco/Ford study, they track engine wear with OCI duration, but they also track vis as well. The major indicator they are tracking is the TCB (tribochemical barrier from oil oxidation). Interestingly, the vis starts out fine, drops from shear, then actually rises again (presumably from excess oxidation). And yet, there was no correlation in the shift in wear; the wear dropped precipitously from the onset and never rose again, despite the trials running out to 15k miles in the OCI. And if there is no correlation, by definition there can be no causation. Hence, in this SAE study, vis was proven to not be as imporant to wear control as the TCB was. Wear, in fact, didn't track with vis at all.
I'm not saying vis isn't important; it most certainly is. But it's only important in terms of controlling wear as one of many inputs. If the outputs are good, the inputs are somewhat moot as long as they're "close enough" the to the expected condition.
This UOA only reiterates stuff we already know from countless other examples here on BITOG:
- new engines experience break in wear above "normal" levels
- fuel dilution is present in DI engines
- unfortunately, most folks don't know how to properly interpret UOA data
When you have time, please consider reading this:
Reviewing UOA Data Used oil analyses (UOAs) are tools. And like most tools, they can either be properly used or misused, depending upon the application, the user, the surrounding conditions, etc.= There are already many good articles and publications in existence that tell us how to interpret...
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