How to Choose Gear Oil for Trucks?

[AdamFitz]

Correct selection of gear oil for trucks is as follows: 1. Determine the quality grade of the oil based on the gear type and working conditions. The selection of gear oil quality grade should be based on the type of main reducer gear and its working conditions. If the main reducer is a hypoid gear with a tooth surface load exceeding 2000MPa, sliding speed over 10m/s, and oil temperature as high as 120~130°C, heavy-duty vehicle gear oil containing a large amount of extreme pressure additives must be used. 2. Determine the viscosity grade based on the minimum ambient temperature and the maximum operating temperature of the gear transmission. The selection of gear oil viscosity grade mainly depends on the ambient temperature. In southern China, No. 90 or No. 140 oil can be selected. In the cold regions of northeast and northwest China, No. 80W/90 or No. 75W/90 oil is suitable, while in other central regions, No. 85W/90 or No. 85W/140 oil is recommended.

[DelTalia]

When selecting gear oil for trucks, I focus on three key aspects: viscosity grade, performance level, and working conditions. The viscosity rating must match the manufacturer's manual. For winter operations in northern regions, 75W-90 provides better low-temperature fluidity, while 85W-140 is more resistant to high temperatures for summer mountain driving. Always choose GL-5 performance grade – its oil film strength withstands heavy loads and hill climbing, whereas standard GL-4 oil tends to fail under pressure. Seafood haulers require rust-proof synthetic oil, while molten steel transporters need extreme pressure-resistant variants. Monitor oil change intervals closely: ore trucks require changes every 10,000 km, whereas regular delivery trucks can stretch to 40,000 km. Last time I cheaped out with a no-name brand, and the gears ended up looking like a dog's chew toy.

[StMorgan]

We truck drivers are most afraid of counterfeit gear oil. Only 80W-90 bought from legitimate channels is reliable—it should smell free of sour odors and appear clear when poured. I have a rustic method to check viscosity: smear old oil on an iron plate and drip new oil next to it. If the new oil spreads faster than the old, it's too thin to handle heavy loads. Tankers and dump trucks need GL-5 full synthetic oil, which costs three times more than regular oil but saves on transmission repairs. When driving in hot weather or on the Yunnan-Guizhou plateau, switch to a higher-grade oil in advance. Older trucks with poor seals should add some leak-proof additive. If the gearbox feels rough when coasting in neutral, it's time to change the oil—don’t wait until blue smoke appears.

[OMia]

Gear oil viscosity grades are like clothing sizes, with GL-5 being the heavy-duty armor. When purchasing, compare the markings on the oil container: look for the API certification label stating GL-5. The lower the 75W number, the better it performs in winter. The higher the following 90 number, the stronger its high-temperature resistance. Manual transmissions and differentials have different oil requirements, so using separate oils is crucial. Mineral oil needs changing every 20,000 kilometers, while synthetic oil can last up to 60,000 kilometers. Vehicles hauling frozen goods should opt for anti-freeze formulations; otherwise, the oil turns to jelly at -20°C. Heavy-duty oil recommended by repair shops can be used, but check for ILSAC certification.