How to choose gear oil? What is the API grade and viscosity label?
Dear friends in the lubrication industry, today let's talk about something practical - how to choose gear oil without stepping on pitfalls! What is the API grade and viscosity label? Why do you change oil more frequently than socks for the same device that others have been using for 5 years without any problems? This article helps you save at least 50% of lubrication costs!
1、 API level: "ID card" for gear oil
API (American Petroleum Institute) divides gear oil into six grades, GL-1 to GL-6, with higher numbers indicating stronger performance. The mainstream now uses three levels: GL-4, GL-45, and GL-46
| API level | Scope of application |
| GL-1 | Pure mineral oil, without additives |
| GL-2 | A small amount of anti-wear agent |
| GL-3 | A manual transmission and rear axle spiral bevel gear for vehicles operating at medium speeds and loads, |
| GL-4 | Various gears, especially hyperbolic gears, used in cars, sedans, and other vehicles that operate at high speeds with low torque and low speeds with high torque. |
| GL-5 | Used for various gears under high-speed impact loads, high-speed low torque, or low-speed high torque conditions. Especially hyperbolic gears |
| GL-6 | Suitable for ultra-high bias hyperbolic gears |
| MT-1 | Non synchronous manual transmissions suitable for use on buses and heavy-duty trucks; Provide performance to prevent thermal degradation of compounds, component wear, and deterioration of seals |
Common consumer traps：
Using GL-4 on hyperbolic gears -3 months full bloom on tooth surface (one repair is enough to buy 10 barrels of oil) Imported equipment blindly using GL-5- excessive lubrication actually increases energy consumption (measured to burn 5% more electricity)
2、 Viscosity selection: not the thicker the better
The SAE viscosity grade is like the "thickness" of gear oil, and selecting the wrong one directly affects the service life of the equipment:
There are currently seven grades in China, among which the viscosity grade of 85W-90 can basically meet the usage requirements of most regions in China and is the most commonly used viscosity grade.
Temperature range for use
| Viscosity grade | 70W | 75W-90 | 80W-90 | 85W-90 | 85W-140 | 90 | 100 |
| Environmental temperature/℃ | -57~＋10 | -45~＋49 | -25~＋49 | -15~＋49 | -15~＋49 | -12~＋49 | -7~＋49 |
Winter label (with W): The smaller the number, the more frost resistant it is
75W: Can be used at -40 ℃
85W: Starting at -20 ℃ without pressure
Summer label: The larger the number, the more heat-resistant it is
No. 90: Eating in Jiangnan region
140: Special equipment for metallurgical furnaces
Gold combination:
Choose 75W-90 in the north → universal for winter and summer without any fuss
Mining vehicles use 85W-140-80 ℃ high-temperature oil film without rupture
3、 The latest trend in the industry: fuel-efficient and long-lasting
Low viscosity:
Secret: New borate additive replaces traditional sulfur and phosphorus formula
Long life technology:
Top grade gear oil can now withstand 80000 hours (≈ 9 years), depending on the oxidation stability index: acid value change ≤ 0.5mgKOH/g.
