Toyota going to the dogs

I am writing to formally challenge the 15,000km service interval specified for the Toyota Vitz. Recommending a 5W-30 semi-synthetic oil for such an extreme distance is a technical failure that compromises engine longevity.Semi-synthetic blends lack the thermal stability required to maintain viscosity over 15,000km, leading to accelerated oxidation and harmful carbon deposits. Industry standards confirm that while full synthetics can manage 10,000–15,000 miles, semi-synthetics typically degrade significantly after just 7,500–10,000km. By pushing these oils to 15,000km, you are prioritising 'low maintenance' marketing over the 'bulletproof' reliability Toyota customers expect.