What are the key differences between hydraulic oil and engine oil?

We all have heard about different types of oils being used in machines and vehicles. Two of the most common ones are hydraulic oil and engine oil. Externally, they may look alike, but their functions, formulations, and applications differ significantly. Using the wrong oil in the wrong place can cause mechanical problems, damage parts, and can reduce performance efficiency.

This blog explains in simple terms how hydraulic oil and engine oil are different, what they do, and how they should be used correctly. 

What Is Hydraulic Oil?

Hydraulic oil is a specialized fluid used to transmit power within hydraulic systems. These systems are commonly found in construction equipment, industrial machinery, lifts, and braking systems. The primary function of hydraulic oil is to provide force through pressure, enabling mechanical movement with minimal resistance.

This oil must maintain a consistent viscosity, resist oxidation, prevent rust and corrosion, and operate efficiently across a wide temperature range. Although it is not primarily designed to handle high heat or combustion, it can withstand high-pressure conditions without foaming or breaking down.

What Does An Engine Oil Do?

Engine oil, on the other hand, is formulated to lubricate the internal parts of combustion engines. It reduces friction between moving parts, dissipates heat, and helps clean the engine by eliminating dirt and combustion by-products. Modern engine oils also include additives like detergents, dispersants, anti-wear agents, and antioxidants.

As engines operate under extreme heat and varying speeds, engine oil must be thermally stable and capable of functioning across a broad temperature spectrum.

Differences Between Hydraulic Oil and Engine Oil

1. Purpose and Function

Hydraulic Oils transmit power in hydraulic systems like brakes and steering systems via fluid pressure.

Engine oil is used to lubricate engine parts, reduce friction between mechanical components, and cool internal combustion engines.

2. Colour and Appearance

Hydraulic oils have a pale colour, with a thinner consistency that makes them suitable for use in hydraulic systems.

Engine oils come in different colours. But the oils which we use daily usually range somewhere between amber to dark brown. Also, they have a thicker consistency than hydraulic oils.

3. Maintenance Requirements

For hydraulic systems, it is important to regularly monitor and maintain check oil levels. This ensures proper performance and prevents any potential leaks.

On the other hand, regular engine oil needs to be checked on a routine basis. This improves engine health and prevents wear and tear on engine components.

4. Viscosity and Flow Characteristics

Engine oils are generally available in different grades like 5W-30, 10W-30. These grades determine the temperature at which the engine oil is capable of functioning.

Similarly, hydraulic oils tend to have a more stable viscosity and are suitable for almost all kinds of climatic conditions.

Can Hydraulic Oil and Engine Oil Be Used Interchangeably?

Although in terms of their composition, hydraulic oil and engine oil might be similar but cannot be used interchangeably. Each of them are constituted from specific additives and have unique viscosity properties which suit different applications. 

For instance, if you use engine oil in a hydraulic system, it can result in reduced performance, overheating, or component damage. So, it is always advisable to use the specified lubricant in the right place to keep your parts running smoothly.

Bottom Line

Using the right oil, whether hydraulic oil or engine oil plays a crucial role in your machine’s operations and longevity. Don’t leave it to guesswork; always follow the owner’s manual or ask a professional which brand to buy from. A small step today can prevent major issues tomorrow.