Excessively high engine oil viscosity can have multiple negative impacts on engine operation, primarily affecting power performance and fuel economy. High-viscosity oil exhibits poor fluidity, increasing frictional resistance in engine moving parts and causing oil pumping difficulties during cold starts-particularly exacerbating startup wear in tropical climates. The engine requires more energy to overcome this resistance, leading to delayed power output, sluggish acceleration response, and potentially a 3%-5% increase in fuel consumption. Moreover, reduced circulation speed of high-viscosity oil impairs heat dissipation. For new vehicles or precision engines, manufacturers typically recommend low-viscosity oils like 5W-30 or 0W-20 to optimize energy efficiency, whereas high-mileage vehicles may use slightly higher viscosity oils to compensate for component wear. Oil selection must strictly adhere to the SAE grade specified in the vehicle manual, balancing high-temperature protection with low-temperature pumpability. Regular oil changes using certified products (e.g., API SN/SP grades) are equally critical, as improper viscosity selection may void warranty coverage.
