Choosing the Right Hydraulic Oil for Your Equipment

When it comes to keeping machinery running properly, hydraulic oil is often overlooked – until something goes wrong.

Using the right oil can make a big difference to performance, efficiency and long-term wear.

What does hydraulic oil actually do?

Most hydraulic oils also contain additives to help reduce wear, prevent corrosion and improve performance.

Hydraulic oil plays a few important roles in your equipment:

• Transfers power through the system
• Lubricates internal components
• Helps control temperature
• Protects against wear and corrosion

If the wrong oil is used, you can end up with reduced performance, overheating or unnecessary wear on components.

What do the numbers mean? (ISO 32, 46, 68)

Those numbers refer to viscosity – how thick or thin the oil is.

• Lower number (32) = thinner oil, flows easier
• Mid range (46) = general purpose
• Higher number (68) = thicker oil, better under load

As a general rule, thinner oils suit cooler conditions, while thicker oils hold up better under heat and heavier workloads.

Why choosing the right grade matters

Getting the viscosity right is key to how your system performs. Hydraulic oil viscosity is rated at 40°C, and changes with temperature – thinner when hot and thicker when cold.

If the oil is too thick:

• Poor flow on startup
• Strain on pumps
• Slower system response

If the oil is too thin:

• Reduced protection under load
• Increased wear
• Loss of efficiency

Hydraulic systems are designed to run within a specific range, so using the correct grade helps everything operate as it should.

What grade should you be using?

There’s no one-size-fits-all answer – it depends on your equipment and conditions.

Things to consider include:

• Type of machinery
• Operating temperature
• Load and working conditions
• Manufacturer recommendations

As a general guide:

• ISO 46 suits most general applications and is commonly used across Australian conditions
• ISO 68 is better for heavier or hotter conditions
• ISO 32 is suited to cooler environments

Common mistakes to avoid

Some common issues we see include:

• Mixing different hydraulic oils
• Using whatever is on hand
• Not checking manufacturer specifications
• Ignoring operating conditions

These can lead to problems over time – even if everything seems fine at first.

Final thoughts

Hydraulic oil might seem like a small detail, but it plays a big role in keeping equipment running efficiently and reliably.

If you’re unsure what grade you should be using, it’s always worth checking and getting it right to help reduce wear and avoid downtime.