[tristor]

Manufacturers are pushing to extend oil change intervals but depending on your climate and driving style you’ll see different oil degradation, and it had nothing to do with differing quality of oil. Oil standards are international.

The only way to know is to consistently and regularly have used oil analysis done. For my part, I change my oil every 3k or sooner because my vehicle gets put on a race track occasionally, which changes wear patterns and an oil change is cheap insurance. For full synthetics on a car which mostly sees highway miles 10k intervals are fine, but 15k and 20k intervals are ridiculous. For most cars in the US which see significant traffic a 5k interval is correct as stop and go traffic is actually harder on the engine than almost anything else.

Side note: A kilometer is just a little over half a mile. A 10k KM OCI is equivalent roughly to a 6500 mile OCI. So there isn’t that much difference between the US and European intervals.