5W30 engine oil is suitable for use in hot weather, as its viscosity design balances low-temperature fluidity and high-temperature protection. The "5" in the grade indicates low-temperature fluidity, providing quick start protection in -30°C environments, while the "30" represents high-temperature viscosity, with a kinematic viscosity of 9.3-12.5 mm²/s at 100°C, making it suitable for operating conditions where ambient temperatures do not exceed 35°C. For most modern vehicles, particularly new Japanese and Korean models or hybrid vehicles, 5W30 fully synthetic engine oil delivers stable oil film strength while optimizing fuel economy. However, if the vehicle is an older turbocharged model, subjected to prolonged high-load operation, or operated in extreme high-temperature regions (such as areas with常年 temperatures exceeding 40°C), upgrading to 5W40 is recommended to enhance high-temperature protection. The final selection should prioritize the vehicle manual's recommendations while considering actual driving conditions.
