Gear oil, Hydraulic oil, and transmission oil

Gear oil, Hydraulic oil, and transmission oil- Explained

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Lubricants are a bit confusing if you are not into them a lot. It seems if they are named lubricants, then their work is of only lubrication. In fact, each one of them has a lot more to do than lubrication.

In this read, you will get an insight into the functions of gear oil, transmission oil, and hydraulic oil.

You must have heard the names of these different types of lubricants used in a vehicle. Their usage is according to their specific requirements. None of them can replace the other one as they all have differences in the formulation, although work is almost similar. Read on to know about each one of them.


Gear oil


The very first lubricant we will talk about is gear oil. As the name suggests, gear oil’s work is to protect the gear against unnecessary friction due to high pressure and speed. Usage of gear oil is in various industries and not only the automotive industry. This oil also works as a coolant and hence cools down the gearbox after the intensive motion of gear parts.

Gear oil has its usage in nearly every industry as every type of machinery requires gear oil for the smooth functioning of its gears. There are different levels of gears used in machines. Low-level gears require gear oil for lubrication and rust protection. On the other hand, high levels of gears also need protection against high pressure. High-speed motion of gears generates this high pressure. For this purpose, high-level gear oils have EP (extreme pressure) additives that protect the gears against high pressure.

The downside of these EP additives is that they contain Sulphur and phosphorus that can corrode the metals like brass and copper. Due to this reason, these EP additives containing gear oils are generally not used for metal parts made of brass and copper. 


Different types of gear oils


GL rating is the basis of the classification of different gear oils. According to the requirements and usage, gear oils are available as G1, G2, G3, and G4. Here G1 is a low-grade gear oil usage of which is for lower levels of gears. G4 is top-level gear oil having EP additives and has its requirement in heavy gearboxes.

Synthetic gear oils are also available with these additives and deliver a higher level of pressure protection. However, mineral oils are also most widely used as they have a higher viscosity than synthetic gear oils.


Hydraulic oil


Hydraulic fluids are used in the hydraulic system for power transfer. Hydraulic systems are highly effective in transferring high powers even when the initial force is low. For instance, vehicle power steering, hydraulic brakes, elevators, and more use the hydraulic system.

Power delivery depends upon the hydraulic fluid used. Hydraulic fluids can deliver high energy due to their high resistance to volume reduction and high viscosity.

In earlier times, the usage of water as hydraulic fluid was in practice. Later on, oils took over the water as water has a lower viscosity, leads to corrosion, and has no lubrication properties.

Today hydraulic fluids are oils having additives for their better performance. These hydraulic fluids work both as a Lubricating medium and coolant that absorbs the heat energy generated due to high pressure. The hydraulic fluid consisting of natural oils is generally flammable, so for this reason, nowadays, the hydraulic fluid having synthetic oils is mainly used.

Mineral oils are also not used directly; the addition of additives makes them ready for usage.



Transmission oil


Transmission fluids are mistaken as the same as gear oil, but they are considerably different.

Transmission fluids are used for automatic transmission, whereas gear oil has its usage in manual transmission. An automatic transmission consists of several parts operating in a planetary system. These parts need much more lubrication and effective power transfer, so transmission fluids have low viscosity.

Transmission fluid lubricates the transmission parts and also delivers power from the oil pump to the clutches. Transmission fluid performs different functions. These functions are cooling, cleaning, heat resistance, and power delivery.

Transmission fluid works as a coolant and absorbs the heat energy generated during the movement of parts. It also has detergent additives that have to clean the buildup in the channels.




Now, you know the difference between gear oil, transmission oil, and hydraulic oil.

Gear oils are used for manual transmission where there is more load and wear and tear. On the other hand, the automatic transmission has a lesser workload than manual transmission and requires transmission fluid. This transmission fluid needs to have lower viscosity. 

Hydraulic fluids have their requirements in hydraulic systems for power transfer from one point to another. For instance, in the case of power steering, a slight movement of the steering wheel generates enough power to rotate the tires. This power transfer is possible only because of the hydraulic system.

Mukesh choudhary
Mukesh choudhary
Age may offer experience but my passion for cars brings me expertise. I am extremely good at one thing and that's writing about cars.

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