Hydraulic Oil 46 vs 68: 7 Key Differences - MrOilGuy (2024)

When working with hydraulic systems, you may have encountered the terms “Hydraulic Oil 46” and “Hydraulic Oil 68.” These two different types of hydraulic oils are used to lubricate and cool the hydraulic systems in various machines, and they differ in their viscosity (thickness of the oil).

Hydraulic Oil 46 has a lower viscosity and medium density, which is more energy efficient for lower temperatures and smoother circulation. However, hydraulic Oil 68 has a higher viscosity and thicker density, which provides better lubrication and wear protection under heavy loads.

Throughout this article, we’ll explore the uses and compatibility of these two grades of hydraulic oil. So keep reading to find out what hydraulic oil is commonly used and which one is recommended.

What are the Differences Between Hydraulic Oil 46 and 68?

Hydraulic Oil 46 vs 68: 7 Key Differences - MrOilGuy (1)

When comparing hydraulic oil 46 and 68, there are several key differences to consider.

  • Viscosity at 40°C
  • Temperature sensitivity
  • Pour point
  • Air release values
  • Application range
  • Shear stability
  • Use in specific equipment

1. Viscosity at 40°C

To understand the differences between Hydraulic Oil 46 and 68, compare their viscosities at 40°C. Viscosity is a measure of an oil’s resistance to flow, and it determines how easily the oil can circulate through the hydraulic system.

Hydraulic Oil 46 has a viscosity of 46 ± 5 cSt at this temperature, while Hydraulic Oil 68 has a viscosity of 68 ± 5 cSt. The numerical disparity between the two viscosities is significant and impacts the flow characteristics of the oils.

In general, higher viscosity oils like Hydraulic Oil 68 provide better lubrication and wear protection at high temperatures and heavy loads. Conversely, lower-viscosity oils like Hydraulic Oil 46 offer improved energy efficiency and flowability at lower temperatures.

2. Temperature Sensitivity

Hydraulic Oil 46 is designed to perform well in cold or winter conditions due to its lower viscosity. This lower viscosity allows the oil to flow more easily at lower temperatures, ensuring smoother circulation and operation of hydraulic systems.

In contrast, Hydraulic Oil 68 has a higher viscosity and is better suited for summer or warmer environments. The higher viscosity provides better lubrication and protection at higher temperatures, preventing excessive oil thinning and maintaining optimal performance.

3. Pour Point

The pour point of Hydraulic Oil 46 and Hydraulic Oil 68 differs, impacting their performance in varying temperature conditions. The pour point is the lowest temperature at which the oil will flow.

Hydraulic Oil 46 has a lower pour point compared to Hydraulic Oil 68. This means that Hydraulic Oil 46 is better suited for colder temperatures, as it can flow at lower temperatures without becoming too thick.

Alternatively, Hydraulic Oil 68 has a higher pour point, making it more suitable for warmer temperatures. When used in cold winter conditions, Hydraulic Oil 68 may become thicker and affect cold start performance.

4. Air Release Values

Hydraulic Oil 46 and Hydraulic Oil 68 differ in air release values, directly impacting their performance in hydraulic systems.

Air release values indicate the speed at which air is released from the hydraulic oil. Hydraulic Oil 46 has an air release value of no more than 10 minutes, while Hydraulic Oil 68 has an air release value of no more than 13 minutes.

The lower air release value of Hydraulic Oil 46 indicates faster air release and better air release performance. This is crucial in hydraulic applications where air bubbles can cause issues such as reduced efficiency, increased heat generation, and damage to system components.

5. Application Range

When selecting between Hydraulic Oil 46 and Hydraulic Oil 68, consider their application range based on factors such as operating temperature and pump type.

Hydraulic Oil 46 is suitable for a wide range of operating temperatures, typically between -20°C to 80°C (-4°F to 176°F). It’s commonly used in systems where the operating temperature remains relatively stable.

On the other hand, Hydraulic Oil 68 is designed for higher operating temperatures, typically between -5°C to 100°C (23°F to 212°F). It’s recommended for systems that experience higher temperature fluctuations or require increased thermal stability.

Also, the type of pump used also plays a role in the selection process. Certain pumps, such as vane pumps, may perform better with Hydraulic Oil 46, while others, like piston pumps, may require Hydraulic Oil 68 for optimal performance.

6. Shear Stability

Shear stability refers to the oil’s ability to maintain its viscosity under the high-pressure conditions and mechanical stress experienced in hydraulic systems.

Hydraulic Oil 68 generally exhibits better shear stability compared to Hydraulic Oil 46. This means that when subjected to significant mechanical stress, Hydraulic Oil 68 is less likely to experience viscosity breakdown, ensuring consistent performance over time.

The superior shear stability of Hydraulic Oil 68 makes it particularly suitable for applications where the hydraulic system operates under heavy loads or experiences continuous high-pressure conditions.

7. Use in Specific Equipment

If you’re deciding between Hydraulic Oil 46 and 68 for specific equipment, consider their differences in viscosity and performance.

Hydraulic Oil 46, with its thinner viscosity, is commonly used in power steering systems, diggers, excavators, and compressors—this type of equipment benefits from a hydraulic fluid that flows easily and provides smooth operation.

Meanwhile, Hydraulic Oil 68, with its thicker viscosity, is suitable for equipment like machining headstocks, tipping gear, and vane and gear pumps. These types of equipment require a higher viscosity fluid to ensure optimal performance and lubrication.

Comparison Table Between Hydraulic Oil 46 and 68

CharacteristicHydraulic Oil 46Hydraulic Oil 68
Viscosity at 40°C (cSt)46 ± 568 ± 5
Temperature SuitabilitySuitable for colder weather; better circulation in low temperaturesSuitable for warmer weather; optimal for summer conditions
Pour PointLower pour point; better performance in cold start situationsHigher pour point may thicken in cold conditions, impacting start-up
Air Release Value (minutes)≤ 10 minutes≤ 13 minutes
Shear StabilitySlightly lower shear stabilityTypically better shear stability, less viscosity breakdown under stress
Common Equipment UsagePower steering, diggers, excavators, compressorsMachining headstocks, tipping gear, vane and gear pumps
Impact on Energy EfficiencyMore energy-efficient in colder conditionsMore energy-efficient in warmer conditions
Compatibility and MixingMixing not recommended, may lead to issuesMixing not recommended, may affect oil quality and system performance

What is hydraulic oil 46 used for?

Hydraulic Oil 46 vs 68: 7 Key Differences - MrOilGuy (2)

Hydraulic Oil 46 is commonly used for various applications, providing effective lubrication and performance in modern hydraulic systems. It’s specifically designed to meet the requirements of hydraulic equipment and ensure smooth operation.

This type of oil has a viscosity grade of 46, which means it has a moderate thickness that allows it to flow smoothly through hydraulic components. Hydraulic Oil 46 suits various hydraulic systems, including industrial machinery, construction equipment, and agricultural machinery.

It’s also commonly used for lubricating bearings and spur gears in machine tools. Its excellent thermal stability and resistance to oxidation make it ideal for high-pressure systems, ensuring optimal performance and preventing component wear.

What is ISO 68-grade hydraulic oil for?

The ISO 68-grade hydraulic oil is commonly used for high-pressure hydraulic systems, providing optimal lubrication and performance. It’s specifically designed for applications where pressures exceed 1000 psi, making it suitable for hydraulics with vane, piston, or gear-type pumps.

This grade of hydraulic oil is capable of withstanding the intense pressure and heat generated by these systems, ensuring smooth operation and preventing wear and tear on the components.

Additionally, 68-grade hydraulic oil can also be used to lubricate lightly loaded reciprocating compressors. Its viscosity characteristics allow it to flow efficiently through the system, providing the necessary lubrication to protect the moving parts.

Can I mix ISO 46 and 68 hydraulic oil?

Mixing ISO 46 and 68 hydraulic oil isn’t recommended due to potential performance compromise and increased mechanical wear.

Hydraulic oils have different viscosity grades, determining their flow characteristics and ability to provide lubrication and hydraulic power. ISO 46 hydraulic oil has a lower viscosity than ISO 68, meaning it flows more easily.

Mixing these two grades can result in an oil with an inconsistent viscosity, leading to inadequate lubrication and reduced hydraulic performance. Also, the different additives and properties in each grade can interact unfavorably, causing corrosion of component surfaces and increased mechanical wear.

Can I use ISO 46 and 68 in my John Deere tractor?

You can use ISO 46 and 68 hydraulic oil in your John Deere tractor. These hydraulic oils were specifically developed for John Deere equipment, but they can also be used in other non-John Deere machines.

ISO 46 and 68 are viscosity grades that indicate the thickness of the oil. ISO 46 oil has a thinner consistency, while ISO 68 oil is slightly thicker. When choosing between the two, consider the operating temperature and the load requirements of your tractor.

ISO 46 oil suits moderate temperature conditions and lighter loads, while ISO 68 oil is better for higher temperatures and heavier loads. Regularly check the oil level and condition to ensure optimal performance and extend the lifespan of your John Deere tractor.

Hydraulic Oil 46 or 68: Choose the Best Hydraulic Oil for Optimal Performance

Like a well-oiled machine, using the right hydraulic oil is crucial for smooth operation. The differences between hydraulic oil 46 and 68 primarily lie in their viscosity. Hydraulic oil 46 is typically used for lighter applications, while hydraulic oil 68 is better suited for heavier machinery.

Choosing the wrong hydraulic oil can lead to various issues, so it’s vital to select the appropriate viscosity and operating temperature for your specific machine.Also, it isn’t recommended to mix these two grades of oil, as it can affect the performance and efficiency of your hydraulic system.

Hydraulic Oil 46 vs 68: 7 Key Differences - MrOilGuy (2024)


What is the difference between 46 and 68 hydraulic fluid? ›

32 is thinner, No. 46 is medium and No. 68 is thicker. Generally speaking, if the temperature is low in winter, use #32 & #46 hydraulic oil with a lower viscosity, and use #68 hydraulic oil with a higher viscosity in summer.

Can you mix 68 and 46 hydraulic oil? ›

As far as possible, it is always best to avoid mixing different hydraulic fluids. This is because the technical properties could be spoiled by chemical reactions between different additives.

What can I use instead of 46 hydraulic oil? ›

"It is a common practice in the construction and mining industries to use engine oil SAE 10, SAE 20 or SAE 30 with the lowest API rating as a substitute for hydraulic oil ISO 32, ISO 46 or ISO 68, respectively for hydraulic systems of heavy equipment.

How to compare hydraulic oil? ›

Hydraulic oil with a high viscosity will be thicker and harder to compress and move, whereas a low viscosity oil will be thinner and pass through much easier. The viscosity is measured in Centistokes (cSt) at temperatures of 40°C or 100°C in a laboratory setting using a viscometer.

What is hydraulic oil 68 used for? ›

Hydraulic 68 uses

Common applications for ISO 68 hydraulic oil include: machining headstocks. centralised lubrication systems. tipping gear.

What is hydraulic oil 46 used for? ›

The hydraulic oil HLP 46 is used as pressure fluid in industrial and mobile hydraulic systems. It must withstand high thermal loads, prevent corrosion when water is supplied and minimise wear when mixed friction occurs. The designation HLP 46 is composed of "HLP" and "46".

Does it matter what hydraulic oil you use? ›

Hydraulic oil viscosity is important for each different application. The wrong viscosity could cause damage to equipment or have poor results in function.

What happens if you mix different hydraulic fluids? ›

"Is it all right to mix an R&O hydraulic oil with an AW hydraulic oil in a hydraulic application?" Mixing oils with different additive packages is never recommended. Doing so could compromise the additive performance of both constituents, cause corrosion of component surfaces and lead to increased mechanical wear.

What is the recommended grade oil for hydraulic system? ›

Common grades include ISO VG 32, 46, and 68 for industrial applications, and AW 32, 46, and 68 for high-pressure systems. Each grade is designed for specific operating conditions and applications. You'll need to match the oil grade with your system's requirements to ensure smooth operations and longevity.

Which oil is best for hydraulic? ›

Hydraulic equipment used indoors under normal service conditions generally use a conventional antiwear hydraulic oil with the appropriate viscosity. The most commonly used viscosities are ISO 32, 46, or 68, since these are able to lubricate and protect the system under the normal range of operating temperatures.

What happens if you mix 32 and 46 hydraulic oil? ›

Mixing oils with different additive packages is never recommended as this could compromise the additive performance, cause corrosion, or increase mechanical wear.

What happens if you put engine oil in a hydraulic system? ›

Formulated without these characteristics, an engine oil will break down far faster and will quickly become ineffective. This will lead to damage to the hydraulic system, leading to expensive repairs or, in worst-case scenarios, the replacement of equipment entirely and the loss of a company's investment.

Should I use 46 or 68 hydraulic oil? ›

It is very popular that the viscosity of No. 46 anti-wear hydraulic oil is thinner than that of No. 68 anti-wear hydraulic oil. If it is winter, the viscosity will be thinner to facilitate circulation; in summer, the temperature is high, and the viscosity is higher.

What happens if you use the wrong hydraulic oil? ›

Whether it is changing hydraulic filters too often or using the wrong type of hydraulic fluid, these errors can lead to serious problems such as unnecessary maintenance costs, increased repair costs, system downtime, premature wear of components, and even catastrophic failure.

What is the equivalent of 46 weight hydraulic oil? ›

You may notice that ISO 46 can replace both 15W and 20W SAE oils. This is because the ISO specifications are broad, and they overlap with SAE weights in some cases. If your tractor or truck calls for 20W hydraulic oil, it may be best to use the thicker ISO 68 in hot temperatures and thinner ISO 46 in cold weather.

What viscosity is 68 hydraulic oil? ›

Typical Characteristics
KV @ 40°C (cSt) ASTM D44566
KV @ 100°C (cSt) ASTM D4458.8
Viscosity Index, ASTM D 2270107
Density @ 15°C kg/L0.868
2 more rows

Does it matter what hydraulic fluid you use? ›

Choosing the right hydraulic fluid is crucial to guarantee the best performance and efficiency of the system. Each fluid has its specific characteristics in terms of viscosity, suitable operating conditions, anti-wear properties, etc.

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