Difference between Transmission Fluid and Hydraulic Fluid

transmission fluid vs hydraulic fluid

The proper functioning of vehicles and machinery relies heavily on their intricate network of fluids. Two of the most important fluids in this network are transmission fluid and hydraulic fluid, both of which play a critical role in transferring power. However, it is important to note that although these fluids share some characteristics, they differ in their specific purposes.

In this blog post, we will explore the unique roles of transmission and hydraulic fluids in various machines, discussing their types, benefits, key differences, and applications.

What is Transmission Fluid?

Transmission fluid is a specialized lubricant essential for the proper functioning of both automatic and some modern manual transmissions. It performs multiple tasks: lubricating gears and bearings to minimize wear, reducing friction between moving parts like the torque converter and clutch/brake bands for smooth gear changes, and sometimes acting as a hydraulic fluid to operate the transmission control system in automatics.

Moreover, it lubricates the parts, adds hydraulic pressure, and provides friction for efficient internal functioning.

Types of Transmission oil

Transmission oil comes in various types and is used for specific  reasons, and these types are discussed below step by step:

types of transmission fluid

1. Manual Transmission Oil:

Manual transmission oil, also known as manual transmission lube or oil, is standard in old automobiles. Manual transmission fluids often made it demanding for car owners to shift in and out of gear smoothly, especially during winter. This is the primary reason many transmission systems use automatic transmission fluid.

2. Automatic Transmission Fluid (ATF):

Automatic transmission fluids (ATF) are specialized oils tailored for vehicle automatic transmissions. They ensure proper valve operation, minimize brake band friction, and facilitate power transfer to the drive wheels.

3. Continuously Variable

Continuously variable transmission fluid is engineered explicitly for advanced SUVs, trucks, and cars. Misusing incompatible fluid can lead to severe issues in these vehicles.

Benefits of Using the Right Transmission Oil

Here are some essential benefits of using transmission oil step by step:

  • Transmission oil effectively lubricates the hypoid gears, reducing friction between moving parts and ensuring improved operating capabilities.
  • The oil protects components from friction and damage during work with additives that provide anti-scoring and anti-wearing properties.
  • Regular transmission oil changes can reduce emissions and small carbon footprints, as fresh oil has optimal engine efficiency.

What is Hydraulic Fluid?

Hydraulic oil is a fluid used in hydraulic systems to transfer power and perform various functions such as lubrication, cooling, and sealing. Its function typically classifies it within a system and can fulfill multiple roles, such as avoiding corrosion, dissipating heat, and transferring hydraulic energy.

Types of Hydraulic Oil

Here are some essential types of hydraulic oil, which are mentioned below step-by-step

types of hydraulic fluid

1. Petroleum-based hydraulic fluids:

Common hydraulic fluids derived from refined crude oil offer improved rust resistance, reduced foaming, and enhanced lubrication. However, their high combustibility requires prioritizing safety during handling.

2. Water-based hydraulic fluids:

Water-based hydraulic fluids, comprising water and additives, come in two main types: water-oil emulsions and water glycols. Water-oil emulsions are cost-effective, fire-resistant fluids with a 35% water and 65% oil composition, while water glycols provide superior viscosity and corrosion prevention.

3. Synthetic blend hydraulic fluids:

Synthetic blend hydraulic fluids excel in high-temperature situations, providing excellent lubrication due to their smooth viscosity. However, they are not environmentally friendly and might not be compatible with certain sealing materials like nitrile.

Know more:Uses and Benefits of Hydraulic Oil

Hydraulic oil vs Transmission fluid

When comparing hydraulic oil and transmission fluid, it’s important to note that hydraulic fluids are used for general power transmission in various machinery, while transmission fluids are specifically designed for transmissions in vehicles.

While some fluids can be used interchangeably in certain situations, following equipment manufacturer recommendations is crucial for optimal performance and longevity.

Following are some major differences between hydraulic oil and transmission oil:

Composition and Additives:

Transmission fluid is enriched with additives to improve lubrication, minimize friction, and shield against wear and corrosion. In contrast, hydraulic fluid incorporates additives for anti-foaming, anti-rust, and anti-oxidation properties, along with viscosity stability under diverse conditions.

Viscosity and Flow Properties:

Transmission fluids maintain stable viscosity across temperatures for smooth gear shifts. In contrast, hydraulic fluids’ viscosity varies based on system requirements and conditions.

Operating Pressure and Temperature Range:

Hydraulic systems endure high pressures, demanding fluids that withstand extreme conditions while ensuring performance and safety. Hydraulic fluids must also remain stable across various temperatures for versatile operation.

Compatibility with Materials:

Transmission and hydraulic fluid must be compatible with system materials like seals and hoses to prevent degradation and leaks, averting system failure.

Also Read:Difference between Transmission Fluid and Engine Oil

Applications of Transmission Fluid and Hydraulic Fluid:

Transmission Fluid:

  • Automobiles (both automatic and manual transmissions)
  • Trucks, buses, and commercial vehicles
  • Agricultural machinery (tractors, harvesters)
  • Construction equipment (excavators, loaders)

Hydraulic Fluid:

  • Hydraulic excavators and cranes
  • Forklifts and material handling equipment
  • Industrial machinery (presses, injection molding machines)
  • Aircraft landing gear and brake systems


Both hydraulic oil and transmission fluid are used for power transmission. However, hydraulic oil has a wider range of applications in various hydraulic systems, including construction equipment, machine tools, and brakes. Transmission fluid, on the other hand, is specifically designed for transmissions in vehicles, either automatic or manual (although the fluids differ for these). Understanding these differences is crucial for selecting the right fluid, ensuring optimal performance, and minimizing maintenance costs.

Shield Lubricants offers a comprehensive range of premium transmission and hydraulic fluids formulated to meet the specific demands of your machinery. Our transmission fluids ensure smooth gear changes and minimize friction, while our hydraulic fluids optimize power transfer efficiency in hydraulic systems.

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