Though there are 4,000 miles on both the engine and the oil, the oil samples each have 2,000 miles on them. What I see here is that there are few additional wear metals on the second sample. Almost if the engine is already broken in. The iron only went up 3 PPM for example during the second 2,000mi interval.
I wondered if the silicon might get filtered out some. The GM oil filter is 30u and the WIX is 20u (I think).
Same for the air filtration. I thought maybe the WIX might filter better and there would be no extra Si. It was practically unchanged. I did keep the OEM air filter to use at a later time. If I conclude it was about the same filtration as the WIX, I will put it back in when it's time for a new one.
Of course all this assumes the UOAs were accurate and a useful indicator. I did not cut open the original oil filter as it would not tell us much. But I will cut this one open just for S&G.
I did just change the oil and oil filter. This time a Motorcraft filter left over from my Navigator - same size.
Ali