5W-40 engine oil performs excellently in hot climates. Its high-temperature viscosity value "40" indicates a kinematic viscosity range of 12.5 to 16.3 mm²/s at 100°C, forming a stable oil film to protect against mechanical wear under high-temperature operating conditions. For older vehicles exceeding 70,000 kilometres, the higher viscosity of 5W-40 helps compensate for component wear gaps. Fully synthetic 5W-40 formulations like Mobil 1 or Shell Helix Ultra feature shear stability (HTHS ≥ 3.5 mPa·s), enabling them to endure sustained ambient temperatures above 40°C. The PAO base oil technology further extends oil change intervals to 10,000 kilometres. Note that if the vehicle manual specifically requires low-viscosity oil (e.g., 5W-30), original manufacturer specifications should be followed to prevent increased oil consumption. Nevertheless, for most vehicles operating under high-temperature and high-load conditions, 5W-40 represents an optimal balance between lubrication protection and durability.
