Can 75w90 Gear Oil Be Used in Summer?
2 Answers
75w90 gear oil cannot be used in summer. Here are the relevant explanations: 1. Viscosity Grade: Gear oils can be divided into single-grade viscosity type and multi-grade all-weather type. The single-grade viscosity type can be further categorized into high-temperature type and low-temperature type. 85w90 gear oil belongs to the multi-grade all-weather type, which has a wider temperature range and can be used all year round. 2. Grade Identification: The W on the viscosity grade identification of gear oil indicates low-temperature gear oil. The number before the W represents the low-temperature viscosity. The smaller the number, the lower the viscosity, the better the fluidity, and the stronger the low-temperature performance. The number after the W represents the high-temperature viscosity. The larger the number, the higher the high-temperature viscosity, and the higher the temperature it can withstand.
I use 75W90 gear oil for my truck running on mountain roads every summer, and it works perfectly fine. The number 90 in this grade is the value designed to cope with high-temperature environments, specifically considering the high temperatures in the engine compartment during summer. Last August, when I drove on the desert highway in Xinjiang, the ground temperature was 60 degrees, and the oil temperature gauge showed 120 degrees, yet the gear shifts remained smooth. Actually, 75W90 is an all-season oil, and its low-temperature startup performance in winter is also excellent. It's a good reminder to check the fluid levels before long summer trips, as evaporation is faster under high temperatures. In my ten years of driving heavy trucks, I've only encountered the transmission overheating protection activating once, and that was due to a clogged radiator.
