Pennzoil Platinum would be alright to run for 12k km?
Most shops here in BC recommends running synthetic oil for around 6k km max... so far i never heard any shop recommending running 10k kms on synthetic.. Even my local dealership said if i want to use synthetic on our minivan( it is still on warranty) to use synthetic for 5k km... that's what they normally recommend for most cars.. 5k km intervals.. but with synthetic.. they said its still the same....
Crazy advice...even for extreme conditions synthetic OCI @ 6k KILOMETERS (4k MILES) is a waste
...synthetics can go 6k MILES (10k KILOMETERS) even under extreme conditions.
...to say "it's still the same" is just ignorance or a sales pitch to get you into the shop more often...
Of course there are those who do change oil, even synthetics, @ 3-4k miles, as in the last century...but modern oils are much better...