What is the difference between gear oil 75w90 and 80w90?
4 Answers
75w-90 and 80W-90 gear oils differ only in viscosity. Below are the viscosity specifications for these two gear oils: 1. 75w-90 viscosity: The kinematic viscosity of 75w-90 gear oil at 100°C is 4.1mm2·s, with a maximum temperature of -40°C to reach 150Pa·s. 2. 80W-90 viscosity: The kinematic viscosity of 80W-90 gear oil at 100°C is 7.0mm2·s, with a maximum temperature of -26°C to reach 150Pa·s.
I've repaired quite a few manual transmission vehicles. The main difference between 75w90 and 80w90 gear oil lies in their low-temperature fluidity. 75w90 flows more smoothly during cold winter starts, with lower viscosity for better gear protection. 80w90 is slightly thicker, making it more suitable for moderate or southern climates. At high temperatures, both maintain the same 90 viscosity rating with equal protective performance. Oil selection depends on temperature: prioritize 75w90 for subzero northern regions to prevent cold-start gear wear, while 80w90 works fine in warmer areas and saves money. I recommend frequently consulting your vehicle manual - mixing oils can cause sedimentation, so always flush old residues before adding new oil. Regular maintenance extends transmission lifespan, saving both money and hassle.
Having driven for many years, I've tried both 75w90 and 80w90. The 75w90 performs exceptionally well in low temperatures, making cold starts much easier; the 80w90 has slightly higher viscosity, which might delay lubrication in winter. Both offer consistent protection when the car is warmed up. Choosing the right oil based on seasonal changes is crucial: in sub-zero environments, 75w90 is a must to prevent transmission stiffness; in consistently warm regions, 80w90 is more economical. Regularly check oil quality and change it, not exceeding 3 years. Mixing oils can lead to sediment buildup and accelerate component wear. Saving money isn't the priority—safety comes first.
Common comparison between 75w90 and 80w90 for vehicle lubrication issues. 75w90 has lower viscosity in cold temperatures and better fluidity; 80w90 is slightly higher and suitable for normal temperatures. The former is recommended for lower cold-start risks, while the latter is applicable in warmer regions. High-temperature protection is the same. Choose oil based on region: use 75w90 in cold northern areas, and 80w90 is fine in the south. Change oil every 2 years to ensure optimal performance.
