My cars have computers that tell when to change oil and usually that is 13,000 miles.
It was the same 15 years ago when we run the same engines on dino oils.
But 3l engine takes 8l of oil, what comparing to 6 quarts in behemoth makes big difference.
I run 10,000 miles on synthetic in my Powerstroke. Again -engine taking 14 quarts of oil. Blackstone did not like high iron after 10,000 miles in F450, but all other parameters were good.
Than again, my vintage Detroit diesel was allowed 100k intervals with testing after 50k and every 10k after.
You will never make sense with statistical changes. Too many variations and too many different design.
Send sample to lab after 5000 and go from there.