Generally Wix lab results are not bad, and the cost is decent. Samples have been known to get swapped by accident at the other prominent labs; it's not unique to Wix. Blackstone certainly has done it; so has Polaris. My point is that you can consider using other lab(s), but that's not going to eliminate the risk of a swapped sample.
I cannot assure you that it got swapped, but it just seems so given the odd additive results. How does it make sense that Ca went down nearly 500ppm in only 2700 miles, but Mg went UP by around 650ppm? Zn and moly also go up after use??? If, as you state, you've been using this same oil brand/grade for the last several OCIs, then we can only conclude one of three things, either ...
- Amsoil has terrible control over their additive package dispersement in blending (this, I highly doubt)
- Wix equipment calibration went off the reservation somewhere between those two oil analysis' (possible, but not probable as most labs are good about taking care of their equipment)
- Wix got a sample mixed up with someone else's (this is far more common and likely because this is a result of human error)
See if you can call the lab directly and speak with them about the results.
I see that Amsoil only has one product in their diesel 10w-40 vis, so it's the AMO you're using here? Perhaps also call them and ask what the VOA results should be.
Here is a VOA from AMO from almost 11 years ago ...
Amsoil AMO 10w40 (API CI-4+, CI-4, CF / SL, SJ, SH), JASO MA, ISO-L-EMA
bobistheoilguy.com
Here is a UOA (gas application but using AMO) from 8 years ago ...
I do these xOCI and UOA to help educate you and I, not for $cost$/time saving(ROE). This oil info is about Amsoil AMO 10-40w. Its 10 mths old, w/15,000 miles on it. I didn't dump/change anything when I took this sample because I wanted to see the results first. The vehicle is a 07 Toyota FJ...
bobistheoilguy.com
As you can see, those both have a huge load of Ca and almost no Mg.
There's a pretty big difference between that and the results you got.
Maybe Amsoil has changed the formulation in the last few years? I would think so, given that the older VOA was CI-4+ and UOA was probably CJ-4.
I don't see any more recent VOAs or UOAs for reference, so perhaps calling them is the best approach.