it may be interesting to you you guys about "synthetic oil life study"
Synthetic Oil Life Study
...We are working on a hypothesis: that the true break-in of an engine is at least 20,000 miles, and that, perhaps, during the first year of an engine's use it would be wise to change more frequently, and only start moving toward extended oil changes once the engine is older...
kaya 20k miles or 32k (km), may nakukuha pa din engine wear (metals) as manifested through their flushing.