When using 5W40 oil as a replacement for 5W30, attention should be paid to the impact caused by the difference in their high-temperature viscosity. It is suitable for high-mileage vehicles (over 100,000 kilometres) or German turbocharged engines, as it can fill wear gaps and reduce oil consumption under high-temperature operating conditions. However, it may increase friction resistance in new or low-mileage vehicles, leading to a slightly slower cold-start response and an increase in fuel consumption of approximately 0.3-0.5 litres per 100 kilometres. If the vehicle's original manufacturer recommends 5W30, short-term use of 5W40 can provide additional protection in hot climates or during aggressive driving, but long-term use may affect fuel economy and power response. Consider upgrading the viscosity only for older vehicles or those with obvious oil consumption issues (oil loss exceeding 0.5 litres every 5,000 kilometres). At the same time, avoid mixing different grades of oil to prevent disrupting the formula balance.
