Hydraulic Oils play an exremely important role in today's operations.  And unfortunately, they can also be extremely confusing when trying to pick the right product for your equipment and job needs.

We've collected a group of Features and their explanations to help you understand how to pick and choose among all the options.

 

ISO Ratings and What they Mean

 

Lists of Features and what they Mean:

 

EP Performance = Extreme Pressure Performance

• What it means: The oil contains special additives that protect metal surfaces under high pressure and heavy loads.

• Why it matters: In hydraulic systems with gears, pumps, or moving metal parts under stress, EP additives prevent wear, scuffing, or welding of metal surfaces.

• Where it's used: Especially important in heavy-duty equipment, industrial presses, construction machinery, and high-load hydraulic systems.

Excellent Filterability

• What it means: The oil passes through hydraulic filters easily and efficiently, even when contaminated with water or dirt.

• Why it matters: Helps prevent clogging or slowdowns in the system, reduces downtime, and extends filter and equipment life.

• Bonus: Good filterability = cleaner system + better energy efficiency.

Together, What "EP Performance + Excellent Filterability" It Means:

If a hydraulic oil states "EP Performance + Excellent Filterability", then that oil can be relied on to have these important characteristics:

• High-stress environments

• Clean and efficient system operation

• Longer equipment life

• Less maintenance hassle

If you're selecting oil for machinery, this combo is a strong sign of a high-quality, heavy-duty hydraulic fluid.

 

Excellent Anti-Wear Protection

• What it means: The oil is specially formulated with additives (like zinc dialkyldithiophosphate, or ZDDP) that create a protective film on metal surfaces.

• Why it matters: It reduces wear and tear on key components like ydraulic pumps, valves, cylinders and gears.

• Hydraulic systems involve high-speed movement and tight tolerances. Without proper protection:

  • Metal parts rub against each other

  • That friction leads to scoring, pitting, or even failure

  • Downtime and repair costs go up

• But with excellent anti-wear protection, your system:

  • Runs smoother and longer

  • Stays efficient

  • Has a longer service life

When to look for Excellent Anti-Wear Protection:

• You especially want this for:

  • High-load or high-pressure hydraulic applications

  • Mobile equipment (like excavators or forklifts)

  • Industrial machinery running continuously

 

Extended Oil Life

• What it means: The oil resists breakdown over time due to heat, oxidation, and contamination.

• Why it matters: Oils that last longer don’t need to be changed as often, which saves:

  • 💰 Money on oil and maintenance

  • 🛠️ Downtime from frequent service

• How it’s achieved: Advanced base oils + antioxidant additives keep the oil stable and clean for more hours of operation.

Pump Durability

• What it means: The oil protects hydraulic pumps (gear, vane, or piston types) from:

  • Wear

  • Corrosion

  • Varnish/sludge buildup

• Why it matters: The pump is the most expensive and critical part of the system. If it fails, the whole system goes down.

• Good hydraulic oil keeps the pump:

  • Running cooler

  • Free from harmful deposits

  • Lubricated under pressure

Bottom Line on Extend Oil Life & Pump Durability:

Hydraulic oil with extended oil life and pump durability gives you:

• Longer maintenance intervals

• Lower operating costs

• Better system reliability

• Extended equipment life

If you're maintaining a fleet, running a shop, or just want fewer breakdowns, this type of oil is absolutely worth it.

 

Thermal Stability

• What it means: The oil resists chemical breakdown at high temperatures.

• Why it matters:

  • In demanding systems (like construction equipment, industrial presses, etc.), oil gets hot.

  • Poor thermal stability = the oil degrades, forms sludge/varnish, and loses performance.

• With thermal stability:

  • Oil stays chemically intact

  • Keeps protecting and lubricating even under heat stress

  • Fewer deposits = cleaner valves, pumps, and filters

Oxidation Stability

• What it means: The oil resists reacting with oxygen over time, especially when hot.

• Why it matters:

  • Oxidation causes:

    • Acid buildup

    • Thicker oil (sludge/gum)

    • Corrosion

  • Long-term exposure to oxygen + heat is the #1 killer of hydraulic oil.

• With oxidation stability:

  • Oil life is extended

  • Equipment stays protected longer

  • Less frequent oil changes = lower maintenance costs

Bottom Line on Thermal & Oxidation Stability

When a hydraulic oil is said to have "Thermal & Oxidation Stability," it's basically telling you:  “I can handle the heat and still perform without breaking down.”

Hydraulic oils with thermal & oxidation stability are ideal for:

• High-temp, high-pressure hydraulic systems

• Equipment that runs long hours or under heavy load

• Reducing varnish/sludge, improving system cleanliness, and increasing reliability

If you want less downtime, longer service intervals, and better pump life—this is a must-have property.

 

 

Resistant to Oxidation

• What it means: The oil doesn’t easily react with oxygen when exposed to heat.

• Why it matters:

  • Oxidation causes the oil to thicken, form sludge, varnish, and acids.

  • These byproducts clog filters, foul valves, and wear out components.

• Result: An oil resistant to oxidation keeps your system cleaner, cooler, and longer-lasting.

Resistant to Viscosity Breakdown

• What it means: The oil maintains its thickness (viscosity) across a wide range of temperatures and operating conditions.

• Why it matters:

  • If oil gets too thin (low viscosity), it loses its ability to lubricate—leading to metal-to-metal contact and wear.

  • If it gets too thick, it causes poor flow and makes the system work harder.

• High-quality hydraulic oils have viscosity index improvers and shear-stable formulations that help them stay in the sweet spot.

Bottom Line on Resistant to Oxidation and Viscosity Breakdown

Hydraulic oil that resists oxidation and viscosity breakdown:

• Keeps systems running cleaner and more efficiently

• Extends service intervals

• Protects components from wear and tear

• Saves you money and headaches in the long run

If you're operating equipment in high-temperature or high-pressure environments, this feature is especially important.

 

Water Separation Performance (a.k.a. Demulsibility)

When hydraulic oil is said to have "Good Water Separation Performance," it means it can quickly and cleanly separate from water if contamination occurs.

• What it means: The oil has the ability to release water, rather than holding it in suspension.

• Think of it like salad dressing: You want the oil and water to separate cleanly—not mix together into a cloudy mess.

• Why It Matters in Hydraulic Systems:

  • Water is a common contaminant in hydraulic systems—from condensation, leaks, or humid environments.

  • If oil traps water, it can lead to:

    • Corrosion of metal parts

    • Reduced lubrication

    • Rusty pumps or valves

    • Microbial growth (yes, bacteria and fungus love oil + water)

• With Good Water Separation:

  • Water drops out and settles to the bottom of the reservoir

  • It can be easily drained without changing the oil

  • The oil stays clear, dry, and high-performing

  • Equipment lasts longer and runs more reliably

• This property is especially critical in:

  • Outdoor or marine environments

  • Food-grade hydraulic systems

  • Systems with high fluid turnover or washdown risk

Bottom Line on Water Separation Performance (a.k.a. Demulsibility)

Good water separation performance = better protection, longer oil life, less corrosion, and easier maintenance.

 

What Is Air Release?

When hydraulic oil is described as having "Excellent Air Release," it means the oil can quickly release trapped air bubbles, which is crucial for maintaining smooth, reliable operation.

• Hydraulic oil can trap air during circulation—especially from:

  • Leaks on the suction side

  • Agitation or turbulence

  • System start-up or maintenance

• Trapped air forms tiny bubbles (entrained air) or foam on the surface.

• Why Trapped Air Is a Problem:

  • Spongy or erratic system response

  • Reduced lubrication (air doesn't lubricate like oil)

  • Overheating (air doesn’t carry heat away effectively)

  • Cavitation (when vapor bubbles collapse inside pumps—very damaging)

  • Oxidation increases (air = oxygen = faster oil degradation)

• What “Excellent Air Release” Means:

  • The oil lets go of trapped air quickly, allowing bubbles to rise and escape at the reservoir.

  • This helps the system:

    • Run quietly and smoothly

    • Maintain consistent pressure

    • Prevent component damage and wear

Bottom Line on the Air Release Feature

Hydraulic oil with excellent air release is especially important for:

• High-speed systems

• Precision machinery

• Systems with tight tolerances

• Anywhere cavitation or foaming could be an issue

If you’re experiencing noisy pumps, jerky actuator movement, or fluid discoloration, poor air release might be the culprit.