Transmission oil classification according to SAE and API

Transmission lubricating fluids are used in gearboxes, transfer boxes, bridges and steering mechanisms. There are many cars where the same engine oil is poured into the gearbox . But in certain mechanisms that are subjected to particularly heavy and complex loads, and where oil and mist are dripping into it, it is difficult to get into it, it is necessary to supply the transmission oil under pressure.

Separate different groups and types of motor fluid. Classification of transmission oil is also different.

Accepted classifications

One of the international classifications is the viscosity division. This classification of gear oils is called SAE. In it, lubricants are divided into seven classes, four of which are winter (indicated by the letter W), and the remaining three are summer. All-season marking assumes double designation, for example, 80W90, 75W140 and others.

Another classification of gear oil, called API, suggests a division into six groups. They are used depending on the purpose, which is why it provides its own type of gear transmission, specific loads and temperature.

Classification of transmission oils according to SAE in general

This classification was developed by the American Society of Engineers. She became widely known. Many motorists know it better than any other.

The viscosity class of the lubricating fluid is found in the instruction manual for each vehicle.

The choice from what this classification of gear oils offers is based on the temperature characteristics of the environment where the car will be used. The viscous properties are determined with respect to the achievement of 150,000 cP by Brookfield. If this value is exceeded, the bearings of the pinion shaft will begin the process of destruction. To avoid this, you should strictly follow the recommendations for low-temperature data, choosing the right lubricant.

If the car is to be operated at a temperature of about minus thirty degrees and below, hydrocracking or synthetic lubricants, as well as semisynthetic viscosities of 75W-XX with a viscosity limit of 5000 cP, will be suitable for MKPP.

High temperature is determined at 100 degrees. At its achievement, the details should not begin to deteriorate, even if it is necessary to be under such influence for 20 hours or more.

Transmission oil viscosity classification: details

Here, as well as in motor, lubricating fluids are divided according to seasonal characteristics:

• Winter - 70W, 75W, 80W, 85W;
• Summer - 80, 85, 90, 140, 250.

In this classification, such a division is conditional, since different manufacturers have their own design features.

But the standard SAE J306, for example, has such requirements, which must correspond to the transmission fluids. So, they should contain the only degree of winter or summer series, or a combination of both degrees. There can not be two winter degrees at once.

In addition, if engine lubricants are designated in the range from 0 to 60, the gearboxes range from 70 to 250.

So the developers tried to prevent possible mistakes in the selection of oil. Thus, if motor and transmission fluids have the same viscosity, SAE will have different values.

API in general terms

The universal classification of transmission oils for all types, alas, has not yet been created. But for the class API for manual gearboxes, it is most convenient to classify lubricants.

According to it, passenger cars use oils of the group GL-4 or GL-5. GL-4 is suitable for mechanics and gearboxes with hypoid or spiral-conical pairs and is used in moderate climatic conditions. A GL-5, except for moderate, can be applied and in severe conditions on different types of transmissions.

Individual API groups

Let us consider in more detail all the groups that represent the API gear oil classification.

Group GL-1 owns mineral lubricating fluids. In these oils, there are no additives, except those that have antioxidant and antifoam properties.

To GL-2 are oils with antifriction additives, which serve for worm gears with low rotating speed.

GL-3 - this lubricant, already possessing a large number of additives, which include, and having wear-resistant properties. They are used in the gearbox with several stages and for steering, in the main and hypoid gears. With oil, helical-conical pairs of gears are used, designed for operation at low speeds and not in harsh conditions.

Group GL-4 has a high percentage of additives. These include those that have anti-seize properties. They are mainly used in machines with conventional gearboxes. Lubrication is able to function properly in such gearboxes, where there are high-speed rotations and small torque or vice versa.

To GL-5 belong lubricating liquids, capable of working in difficult conditions, where it is necessary to exert much effort and overcome heavy loads. Such oils are used on different models of cars and motorcycles. Applicable for hypoid gears, pairs of gears working with impacts. Lubricants contain a large number of additives based on serophosphorous elements and reduce the likelihood of metal scoring.

GL-6 oils provide good performance even under harsh operating conditions. They effectively withstand rotation speed, high torques and shock loads. They are characterized by the presence of the greatest number of antiseizant additives compared to the rest of the groups. But the oils of this group are not used often.

The main number of transmission oils is made on a mineral basis. Synthetic is used very rarely.

Other Classifications

Classification of transmission oil according to SAE and API is the most common. But there are other divisions. For example, a separate category includes lubricants for automatic gearboxes. They are not covered by the API as a classification of gear oil. "Zik", "Total", "Mobile" and other manufacturers are guided by their own indicators in the manufacture of lubricating fluids.

ATF classification

Oils for automata are often painted in a bright color, so that the car enthusiast does not confuse and does not fill it in the manual. Also, mixing of colored liquids is not allowed,

Classification for automatic transmission, which would be as unified as for the ICIE, they do not. Therefore, the issue is the manufacturers themselves. So, in General Motors use classification Dexron, and in Ford - Mercon.

Classification of ZF

Widely known is the classification of the company Zahnradfabrik Friedrichshafen, shortly ZF. It is the leader among European manufacturers of gearboxes and engine installations. Having developed its own classification, the company proposes to focus on their classes in terms of quality and viscosity.

For each CP, their oils are allowed. In division, both alphabetic code and digital are provided.

What to base on when choosing

Classification of transmission oils by API, SAE and so on greatly facilitates the choice. But, getting a lubricant, you should also understand what tasks it should solve. Among them are:

• Preventing too much friction and increased wear on the surfaces of gears or other transmission components;
• The energy expended due to the creation of the film must be reduced;
• Creation of heat removal;
• Stopping or minimizing the oxidation process;
• The absence of a negative effect on the reaction of the transmission parts on the surface;
• Not reacting with water;
• Preservation of initial properties during long-term storage;
• Reduction of noise and vibration arising during transmission work;
• Non-release of toxic fumes when heated.

Correctly selected transmission oil will successfully solve its tasks and help prolong the life of the mechanisms.