Regarding the question of whether higher viscosity oil should be used in older engines, a comprehensive judgment must be made based on the vehicle's condition and operating environment. If the vehicle has exceeded 100,000 kilometres and exhibits issues such as slight oil burning, increased cold-start noise, or reduced power, upgrading to 5W-40 fully synthetic oil can enhance high-temperature protection, improve sealing, and reduce oil consumption-this is particularly suitable for German turbocharged models or vehicles operating in prolonged high-temperature environments. Note that turbocharged models must comply with original manufacturer certification standards (e.g., VW 502.00), while China 6-compliant vehicles should prioritize low-ash formulations to prevent particulate filter clogging. It is advisable to regularly monitor oil consumption, replace oil every 8,000 to 10,000 kilometres, and adhere to the manufacturer's recommended viscosity in the vehicle manual, adjusting the viscosity grade only when evident wear symptoms occur.
