How many kilometers should SM-grade engine oil be replaced?

[DeJonathan]

If it is fully synthetic lubricating oil, perform maintenance every 10,000 kilometers or once a year. If it is semi-synthetic lubricating oil, perform maintenance every 7,500 kilometers or every eight months. Engine Oil: Engine oil, also known as lubricating oil, as the name suggests, its most important function is lubrication. This is why some manufacturers in the market use the so-called "nano" concept, claiming it can better adhere to various components and provide superior lubrication. However, based on practical applications in automotive repairs, the effect is not very noticeable. Factors Affecting Oil Change: If high-quality oil is used, the oil change interval can be appropriately extended. However, it is also necessary to make a judgment based on the engine model; higher-grade oil is not always better. The oil change cycle is influenced by multiple factors such as vehicle condition, driving intensity, and air environment.

[JakeMarie]

As a seasoned driver with over a decade of experience, I recommend changing SM-grade engine oil every 8,000 to 10,000 kilometers. If you frequently encounter city traffic jams where the engine often operates at low RPMs (increasing carbon buildup risk), changing at 8,000 km is safer. For highway-heavy driving where oil degrades slower, you may extend intervals to 10,000 km. However, remember to check oil level and color via dipstick every 2,000 km – if it appears black and sticky, replace it immediately. Engine oil acts as the lifeblood of your motor; its protective properties deteriorate over time. Don’t push beyond 15,000 km to save money – cylinder scoring repairs could cost dozens of oil changes combined.

[DelElizabeth]

Tested oil degradation data under different operating conditions. For vehicles mainly driven by highway cruising, the total base number of SM-grade oil can still remain above 2.5 mgKOH/g at 11,000 km; while for taxis with frequent start-stop cycles, the acid value skyrockets after 6,000 km. It is recommended that ordinary car owners take the median value of 8,000 km as a benchmark, while paying attention to three signals: increased abnormal noise during cold starts, sluggish power during sudden acceleration, and the oil smelling burnt. If any one of these three signs appears, regardless of the mileage, it's definitely correct to go for maintenance immediately.

[DeCooper]

SM is an outdated grade in the API standard, and SP grade is now mainstream. For cars produced before 2020 using SM oil, mineral oil degrades after 5,000 km, semi-synthetic lasts up to 7,000 km, and full-synthetic barely reaches 10,000 km. However, note harsh conditions: frequent driving on dusty roads shortens the interval by 30%, high summer temperatures reduce it by 20%, and frequent auto start-stop operation cuts another 15%. My advice is to unscrew the oil cap after refueling to check. If you find milky white emulsification or sludge deposits, even at just 3,000 km after an oil change, it needs immediate attention.