http://www.macallister.com/187/oil-condition-analysis.htm
Quote:
Soot
Soot is found only in engine oil. It is the insoluble residue of partially burned fuel. It is held in suspension by the oil additive package and causes engine oil to turn black. When soot drops out of suspension in the oil, it contributes to additive depletion and eventually increases oil viscosity. Heavy concentrations of soot can cause bearing damage by starving contact surfaces of lubrication.
Oxidation
Oxidation occurs in transmission, hydraulic and engine oils when oxygen molecules chemically join with oil molecules. This chemical reaction is
accelerated by high oil temperatures, glycol contamination from engine coolant, the presence of copper, and from extended oil change intervals. Oxidation causes the oil to thicken, form acids, and lose lubrication qualities, which threatens the life of your components. Oxidized oil will cause deposits on engine pistons and valves, stuck rings, and bore polishing. In hydraulic systems and transmissions, it can cause valve scuffing and sticking.
Nitration Products
Nitration occurs in all engine oils, but is generally only a problem in natural gas engines. Nitrogen compounds from the combustion process thicken the oil and reduce its lubricating ability. If nitration continues unchecked, it can result in filter plugging, heavy piston deposits, lacquering of valves and pistons, and eventual failure.
So, Amsoil's basestock normally start with a higher TAN and TBN. So, there is a measure of oxidation resistance, but it's not so much if another oil would do better, but more like what is your engine going to do to 'any' oil with the current long-highway mileage. Normally, this is considered fine for the OCIs and is probably the most you will get out of any oil at this current service for this application.
If you short-tripped more, but got less mileage as fast you could run longer in time, but short-tripping will also bring the TBN down in quick fashion.
Again, this could be from the ecoboost / fuel setup. I'm not very familiar with this application. I recall vaguely a few years ago there were several DI engines getting fuel dilution and shearing the oil some, but you didn't have that in your case.
I would 'most' be concerned if oxidation lead to the point where enough deposits would cause problems for the Ecoboost's long-term functionality?
As long as you use a capable extended performance oil filter and keep intervals at this cap you are probably fine. For peace of mind, you could once a year run an idle oil flush or use a top-end combustion chamber cleaner. Most concern with oxidation is the deposits and it's essentially the oil saying, "Hi, I'm starting to get beyond my limits of holding this crud in suspension". If that makes sense. The length from the point this UOA is to the point deposits are / would become an issue I do not know. It's only a dynamic understanding, but monitoring soot / insols is a good start, IMO. TAN is a number to note, but with Amsoil recall it starts higher than most other oils and generally speaking that's why TBN is more reliable. Oil's capability vs. inconclusive random TAN without data points to infer anything off of that itself. Enter the insols / soot.
Besides, the numbers look great otherwise. At least the oil isn't shearing, etc. You just might have a tad more deposits from longer continuous duty cycles if the oil is actually letting them go?