In case you didn't see it, HPL Dave stated that 7ppm of the Si in the virgin oil is a defoamer.
Exactly ... The anti-foam agent only accounts for a decreasing portion of the increasing Si.
Here's the numbers: 11, 11, 15, 25 (taken every 5k miles of this OCI).
The anti-foam is now only about 28% of the total Si count.
I seriously doubt the anti-foam is increasing itself as the OCI matures, so it's likely that the true source of the increase is silica and not silicone.
So here's the $64k question ...
Is the Si going up because it, too, is being released by the cleaning effects of the esters, just like our theory of the hard-carbon? Is there dormant Si trapped in hidden areas of the engine now re-emerging into the oil sump? I honestly don't know; it's probably as plausible as the carbon theory. The thing is that we have so few examples of these super-premium lubes introduced into high mileage engines. Wayne didn't start using this lube at mile 1, for the total of 132k miles; he just started using it when the vehicle already had over 100k miles on it. So, is the increase of wear metals due to the scrubbing clean of junk previously left behind? Or is there a seperate and distinct wear-inducing issue afoot? Is this a coincidence that the insolubles found and Si are both increasing, or are they linked?
Here's the potential cause/effcts in summary:
*note: a wild card here is the unknown about how the oil filter may or may not have been loaded such that it was potentially in bypass
1) the insolubles and Si both are increasing due to esters cleaning out old stuff - the increase of elements causing wear are related; this is causing higher wear and will be temporary (one root cause is revealing two related wear-inducing elements)
2) the insolubles and SI are unrelated in increase; the insolubles are ester driven and the Si is ingestion driven (two unique root causes in coincidence)
One variable has already been manipulated; the oil filter has been changed at this most recent UOA. That may or may not bring contamination down, and thus have a positive effect on the wear trends. If the wear comes down, then perhaps the OCI can continue. If the filter changes does not reduce wear, then it's time for an OCI.
The thing to do here is keep on with the current plan. Run the lube and take another UOA in 5k miles; see if the wear trends continue, or taper off. If the wear increases in this next UOA, I would say it's time for a OCI reset, then pick the plan back up.