What gear oil is better

Many car owners do not know which transmission oil is better to use, although not only the productivity and quality of the power plant, but also the service life of the transmission as a whole depends on it. After all, all moving parts of the gearbox have to cope with heavy loads and strong friction. So, today we consider in detail what kind of oil to fill in a manual gearbox, and which one is better suited for the automatic gearbox.


  • 1 Selection of gear oil
  • 2 Viscosity index
  • 3 Operational class
  • 4 Oil change

Selection of gear oil

What oil to pour into the box

In most cases, all-season oils are used for gearboxes, for example, 75W-80

You can find out which oil to pour into the box of your car, from the operational guide or from the service book. This kind of documentation is attached to each car. When choosing a gear lubricant, it is extremely important to focus on the information provided by the manufacturer. The oil used in modern machines has two main criteria: viscosity and operating class. In other words, the oil is of different viscosity (denoted according to the SAE standard) and a different class of operation (denoted by the abbreviation GL: GL-1, GL-2, etc.). These are the main characteristics of transmission oils.

It is worth knowing that for automatic transmissions use of a special lubricant - ATF or Automatic Transmission Fluid is provided. It has a lower viscosity coefficient than conventional gear oil.

Viscosity index

Choosing a suitable viscosity coefficient, you must first focus on the temperature prevailing in your region. According to SAE standards, transmission fluid is divided into three types depending on the season:

  1. The indices of oils for the summer season are SAE 20, 30, -, 60.
  2. For the winter season - SAE 0w, 5w, ..., 25w (w - from the word winter, that is, winter);
  3. The indexes for all-season type oils (double indexes are used for designation) are SAE 0w-30, 5w-40, 10w-40, 20w-50, 75w-90.
See also: Changing the oil in the gearbox mechanic

The required viscosity index for the gear box is precisely indicated in the machine’s operating manual. But as a rule, in order to save use a working fluid all-season type 75w-90, 80w-90.

Service class

what oil to pour into the automatic box

For automatic transmissions, there is a special lubricating fluid - ATF.

According to quality indicators, gear oil is divided into several operational classes. The classification of these groups was developed and systematized by the United States Petroleum Institute, in short, the API. The designations of lubricants according to API are divided into five main classes: GL-1, ..., GL-5. The required indicator of oil quality for each transmission is different and depends on the technical characteristics of the transmission system. Information about what kind of oil to pour into the box, taking into account the quality indicator, can be obtained only from the manufacturer of your car. This information is written in the service book or in the reference book on the use of the car.

Manufacturers usually recommend using GL-4 oil. For lubrication of drive axles, as well as for gearboxes equipped with hypoid gears, an API GL-5 fluid is usually used. For lubricating all-wheel drive transmissions, both automatic oil (ATF) and oils of classes GL-4 and GL-5 are usually used.

Change of oil

It is better to change the transmission fluid in a specialized technical center, after every 30-100 thousand kilometers. In the gearbox, you need to fill the type of lubricant, which is specified by the manufacturer in the relevant documentation. Some automakers may also recommend certain brands.