Whether a 7-month oil change interval is too long needs to be comprehensively evaluated based on the oil type and vehicle operating conditions. If fully synthetic oil is used with an annual mileage under 10,000 kilometres, a 7-month interval falls within the reasonable range; however, for mineral or semi-synthetic oils, or vehicles operating under severe conditions such as frequent short trips, high temperatures, or dusty environments, the interval should be reduced to 6 months or sooner. Fully synthetic oil, with its stable molecular structure and superior high-temperature oxidation resistance, can typically maintain optimal performance for 1 year or 10,000 kilometres under normal driving conditions, whereas semi-synthetic and mineral oils, having weaker oxidation resistance, should be replaced within 7-8 months and 6 months respectively. Special attention should be paid to turbocharged engines, older vehicles (over 5 years), or stop-and-go traffic conditions, as these accelerate oil degradation-even with fully synthetic oil, the interval should be shortened by 20%-30%. New vehicles during the break-in period or those stored for extended durations (exceeding 3 months) require more frequent maintenance to ensure the engine lubrication system remains in optimal condition.
