Hydraulic Oil Vs Engine Oil: Which is Best for Your Machinery?

When it comes to lubricants, many operators wonder: Are engine oil and hydraulic oil interchangeable? The short answer is NO! These oils serve different purposes, and using the wrong one can cause serious equipment damage.

In this guide, we’ll explain:

• What are hydraulic oil and engine oil?

• How they differ in composition and performance

• Whether they can be mixed

• Expert tips on choosing the right oil for your equipment

What is Hydraulic Oil and How Does It Work?

Hydraulic oil is a specialised fluid designed to transmit power in hydraulic systems, such as those found in excavators, cranes, and presses.

Engine oil, on the other hand, is formulated to lubricate the internal parts of an engine and protect it from heat and friction.

Key Properties and Functions of Hydraulic Oil

• High thermal stability – withstands extreme temperatures

• Anti-wear additives – protects hydraulic components under heavy loads

• Corrosion protection – prevents rust and oxidation

• Power transmission – ensures smooth movement in hydraulic systems

Hydraulic oil also acts as a coolant and helps seal system components to prevent leaks.

What is Engine Oil and Its Primary Role?

Engine oil is formulated for internal combustion engines to lubricate moving parts and reduce friction.

Essential functions of engine oil:

• Heat resistance – protects against high engine temperatures

• Detergent properties – keeps engines clean and free of deposits

• Oxidation stability – prolongs oil life

• Improved fuel efficiency – by reducing friction and wear

Engine Oil vs. Hydraulic Oil: The Key Differences

While both are lubricants, their additive packages and viscosity requirements differ significantly:

Bottom line: These oils are not interchangeable.

Why Engine Oil is Unsuitable for Hydraulic Systems

Engine oil lacks the additives required to handle high-pressure, high-load environments of hydraulics. Using it can cause:

• Seal damage

• Overheating

• Premature component failure

  
  

Why Hydraulic Oil Should Never Be Used in Engines

Hydraulic oil cannot protect engine components under combustion heat and pressure. It also has a lower flash point, making it more likely to ignite and posing safety risks and engine failure.

Expert Tips: Choosing the Right Oil for Your Equipment

• Always follow your OEM recommendations for oil type and viscosity.

• Consider operating conditions (temperature, pressure, load).

• Schedule regular oil analysis to maintain performance and prevent costly breakdowns

FAQs

Q: Can I use engine oil instead of hydraulic oil in an emergency?

A: No. Even short-term use can cause severe damage to hydraulic systems.

Q: Is universal tractor oil a safe alternative?

A: UTOs are designed for specific applications in agriculture but are not suitable for all machinery. Always check your OEM guidelines.

Need Help Selecting the Right Oil?

At Lister Fluid Power, we specialise in providing high-performance hydraulic oils that keep your equipment running smoothly. Our experts can help you navigate OEM specs, operating conditions, and performance requirements to find the perfect solution.

Contact craig.thomas@lister.co.uk today to learn more about how Lister Fluid Power can support your machine lubrication needs and keep it in peak condition.

Written By Craig Thomas

Craig Thomas brings over 30 years of expertise in fluid power solutions and heads the fluid power division at James Lister and Sons Co., based in Sandwell Industrial Estate, England. When he’s not busy working on product innovation, Craig shares his knowledge about the fluid power industry through blogs and LinkedIn. Connect with Craig today!