Hydraulic Oil for Industrial and Mobile Equipment

Hydraulic oil transfers power through hydraulic systems while also helping lubricate pumps, valves, cylinders, bearings, and other moving components.

The right hydraulic fluid depends on the equipment manufacturer’s specifications, operating temperature, system pressure, required viscosity, and any special requirements such as fire resistance or zinc-free chemistry.

Keller Heartt carries hydraulic oils from TRUEGARD, Shell Tellus, Mobil, Houghton, and other manufacturers in multiple viscosity grades and package sizes, including 5-gallon pails, 55-gallon drums, and bulk totes. 

How Do I Choose the Right Hydraulic Oil?

Start with the viscosity grade recommended by the equipment manufacturer.

For many industrial hydraulic systems, the most common choices are ISO VG 32, 46, and 68. These numbers describe the oil’s viscosity at a standardized temperature, not its quality level.

The correct choice should always be based on the hydraulic system specification rather than temperature alone.

For example, Mobil’s DTE 20 series aligns DTE 24 with ISO VG 32, DTE 25 with ISO VG 46, and DTE 26 with ISO VG 68.

What Does AW Mean in Hydraulic Oil?

AW stands for anti-wear. Anti-wear hydraulic oils contain additive packages designed to reduce wear in pumps, valves, and other hydraulic components where metal surfaces operate under pressure.

These fluids may also provide:

• Oxidation resistance
• Corrosion protection
• Foam control
• Water separation
• Air release
• Deposit control

TRUEGARD AW 32, 46, and 68 are examples of anti-wear hydraulic fluids currently available through Keller Heartt.

AW 32 vs. AW 46 vs. AW 68: What Is the Difference?

The primary difference is viscosity.

AW 32

AW 32 is a lighter hydraulic oil. It is commonly specified where a lower-viscosity fluid is required, including some equipment operating in cooler conditions.

AW 46

AW 46 is a medium-viscosity hydraulic oil and is widely used in industrial and mobile hydraulic equipment.

AW 68

AW 68 is a heavier hydraulic oil and may be specified for equipment operating at higher temperatures or systems designed around a higher-viscosity fluid.

Standard vs. High-Viscosity-Index Hydraulic Oil

Some hydraulic equipment operates across a relatively stable temperature range. Other systems may experience major temperature swings between startup and full operation.

A high-viscosity-index hydraulic fluid is formulated to maintain more consistent viscosity as temperature changes.

Shell describes Tellus S2 MX as a conventional monograde hydraulic oil and Tellus S2 VX as a fluid designed for broader temperature ranges.

This can make higher-viscosity-index fluids particularly useful for:

• Mobile equipment
• Outdoor machinery
• Cold starts
• Equipment exposed to seasonal temperature changes

TRUEGARD Hydraulic Oil

TRUEGARD anti-wear hydraulic oils are available in multiple viscosity grades, including AW 32, AW 46, and AW 68.

These fluids are designed for industrial and mobile hydraulic systems where anti-wear protection, oxidation resistance, corrosion protection, and fluid stability are important.

Keller Heartt also carries zinc-free TRUEGARD hydraulic fluids for applications that require an ashless additive system.

Shell Tellus Hydraulic Oil

The Shell Tellus family includes hydraulic fluids designed for different equipment and operating environments.

Shell Tellus S2 MX

Tellus S2 MX is designed as a robust industrial hydraulic oil with strong wear protection and long fluid life. Shell positions it particularly for stationary industrial equipment.

Shell Tellus S2 VX

Tellus S2 VX is designed for applications that experience a wider temperature range, including mobile equipment and systems exposed to changing ambient conditions.

Shell also offers zinc-free and synthetic hydraulic-fluid families for equipment with more specialized requirements.

Mobil DTE Hydraulic Oil

Mobil DTE 20 Series oils are anti-wear hydraulic fluids designed for high-pressure hydraulic systems, servo valves, and numerically controlled machine tools.

Mobil lists:

• DTE 24: ISO VG 32
• DTE 25: ISO VG 46
• DTE 26: ISO VG 68

The series is formulated for oxidation resistance, wear protection, water separation, and deposit control.

What Is Zinc-Free Hydraulic Oil?

Traditional anti-wear hydraulic oils often use zinc-containing additive chemistry.

A zinc-free, or ashless, hydraulic oil uses an alternative anti-wear additive system and may be specified for:

• Equipment containing certain sensitive materials
• Environmentally sensitive operating areas
• Applications with OEM requirements for zinc-free chemistry
• Facilities that specifically prohibit zinc-based additives

TRUEGARD currently offers zinc-free AW 32 and AW 46 hydraulic fluids.

The fluid should still meet the required viscosity and equipment specifications before replacing a conventional anti-wear oil.

When Is Fire-Resistant Hydraulic Fluid Needed?

Some hydraulic systems operate near:

• Open flames
• Furnaces
• Forging operations
• High-temperature processing equipment
• Other ignition hazards

In those environments, a conventional petroleum-based hydraulic oil may not be appropriate.

Houghton-Safe 620 is a water-glycol fire-resistant hydraulic fluid designed for hydraulic systems operating near open flames and high-temperature areas. Keller Heartt lists it as Factory Mutual approved for fire-resistant applications.

Hydraulic Oil for Manufacturing and Machine Tools

Hydraulic systems are used throughout manufacturing facilities to power:

• CNC and machine tools
• Injection molding machines
• Presses
• Material-handling equipment
• Industrial lifts
• Automated equipment
• Hydraulic power units

For machine shops, hydraulic fluid selection is especially important because systems may operate alongside cutting fluids, way oils, and other lubricants.

Selecting products with the correct viscosity, water-separation characteristics, wear protection, and compatibility can help support reliable hydraulic operation.

Hydraulic Oil Cross-Reference Guide

Keller Heartt's oil cross-reference guide can help compare equivalent viscosity grades across TRUEGARD, Shell Tellus, and Mobil DTE hydraulic fluids.

Keller Heartt's current cross-reference also includes high-viscosity-index, zinc-free, and synthetic hydraulic oil options.