Can You Mix 32 and 46 Hydraulic Oil?

Can You Mix 32 and 46 Hydraulic Oil? Yes, you can mix ISO 32 and ISO 46 hydraulic oil.

Hydraulic systems require the use of specific hydraulic oil to operate effectively. Viscosity, a measure of an oil’s thickness, plays a crucial role in determining the performance of hydraulic systems.

This article aims to address the question of whether it is possible to mix hydraulic oil with different viscosity grades, specifically 32 and 46.

Mixing 32 and 46 hydraulic oil is possible, but it is essential to consider certain factors. Compatibility between the oils and the equipment being used is crucial. Additionally, the resulting viscosity and performance of the hydraulic system may be affected. It is advisable to consult the manufacturer’s recommendations or seek expert advice before attempting to mix different viscosities of hydraulic oil. Proper maintenance, including system flushing, may also be necessary when transitioning between oil types.

Can You Mix 32 and 46 Hydraulic Oil

AspectMixing 32 Hydraulic OilMixing 46 Hydraulic Oil
ViscosityLower viscosityHigher viscosity
Temperature rangeSuitable for lower temperaturesSuitable for higher temperatures
PerformanceMay result in reduced performance due to thinner oilMay result in reduced performance due to thicker oil
LubricationMay provide less lubricationMay provide better lubrication
Wear protectionMay offer less wear protectionMay offer better wear protection
EquipmentMay be suitable for lighter-duty equipmentMay be suitable for heavier-duty equipment
Fluid compatibilityMay not be compatible with certain systems designed for 46 oilMay not be compatible with certain systems designed for 32 oil
CostGenerally lower cost compared to 46 oilGenerally higher cost compared to 32 oil

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Understanding Viscosity Grades

Viscosity GradeDescriptionApplication
0WVery low viscosityExtreme cold temperatures
5WLow viscosityCold temperatures
10WModerate viscosityCold to moderate temperatures
15WModerate viscosityModerate temperatures
20WModerate viscosityModerate to warm temperatures
30Higher viscosityWarm temperatures
40Higher viscosityHot temperatures
50Higher viscosityVery hot temperatures
60Higher viscosityExtreme hot temperatures

Viscosity grades, such as ISO 32 and ISO 46, indicate the oil’s thickness or resistance to flow at different temperatures. The numbers associated with these grades signify their viscosity range.

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Lower numbers represent oils with lower viscosities, indicating they are thinner and flow more easily. Conversely, higher numbers represent oils with higher viscosities, indicating they are thicker and flow less easily.

What do the numbers represent?

The numbers in ISO 32 and ISO 46 represent the kinematic viscosity of the oil measured in centistokes (cSt) at 40 degrees Celsius. ISO 32 oil has a kinematic viscosity between 28.8 and 35.2 cSt, while ISO 46 oil has a kinematic viscosity between 41.4 and 50.6 cSt. These values help determine the oil’s performance in various hydraulic applications.

Differences between ISO 32 and ISO 46 oils

DifferencesISO 32 OilISO 46 Oil
ViscosityLower viscosityHigher viscosity
Temperature RangeSuitable for low to moderate temperaturesSuitable for moderate to high temperatures
Film ThicknessThinner filmThicker film
Load-Carrying CapacityLower load-carrying capacityHigher load-carrying capacity
FrictionLower frictionHigher friction
Energy EfficiencyMore energy efficientLess energy efficient
Component ProtectionMay provide less protection for high-pressure systemsProvides better protection for high-pressure systems
ApplicationSmaller machines, light-duty equipmentLarger machines, heavy-duty equipment
Common UsesSmall hydraulic systems, compressors, refrigeration systemsIndustrial hydraulic systems, gearboxes, circulating systems

ISO 32 hydraulic oil is typically recommended for systems operating in colder temperatures or those requiring higher levels of fluidity. It offers excellent flow characteristics and provides better start-up performance in low-temperature environments.

On the other hand, ISO 46 hydraulic oil is more suited for systems operating in warmer temperatures or those requiring higher levels of viscosity. It offers better stability and lubrication in high-temperature conditions.

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Factors to consider when mixing hydraulic oils

Factors to ConsiderDescription
CompatibilityEnsure compatibility between different hydraulic oil types, including base oils, additives, and viscosity modifiers.
ViscosityConsider the viscosity grades of the oils being mixed and ensure they are within an acceptable range for the hydraulic system’s operating temperature and equipment requirements.
Additive PackagesPay attention to the additive packages present in each oil and their compatibility. Mixing oils with different additives can lead to unpredictable performance or even chemical reactions.
Fluid PropertiesConsider the desired properties of the hydraulic fluid, such as oxidation resistance, anti-wear properties, corrosion protection, and foam control. Mixing oils with conflicting properties may compromise performance.
Equipment Manufacturer RecommendationsCheck the equipment manufacturer’s guidelines to see if they permit or provide recommendations for mixing hydraulic oils. Some manufacturers may have specific requirements or restrictions.
Testing and MonitoringConsider performing compatibility tests or oil analysis to assess the potential effects of mixing oils. Regular monitoring of the fluid condition can help identify any issues that may arise from mixing.
DocumentationMaintain proper documentation of the oils being mixed, their proportions, and any relevant test results. This information can be useful for troubleshooting or future reference.
Expert ConsultationIf in doubt or dealing with critical systems, consult with a lubricant specialist or the equipment manufacturer to ensure appropriate mixing practices are followed.

While it is generally recommended to use the hydraulic oil specified by the equipment manufacturer, certain situations may necessitate mixing different viscosity grades.

However, several factors should be considered before attempting such a mixture.

Compatibility of additives

Hydraulic oils may contain various additives that enhance their performance and protect the hydraulic system. When mixing different viscosity grades, it is essential to ensure that the additives are compatible with each other. Incompatible additives may lead to chemical reactions that can degrade the oil’s properties and compromise system performance.

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Viscosity blending

When mixing hydraulic oils with different viscosities, it is crucial to consider the resulting viscosity. The resulting viscosity will lie between the viscosities of the oils being mixed. Proper blending techniques should be employed to achieve the desired viscosity range. This process helps ensure the hydraulic system operates within the acceptable parameters.

Consequences of mixing different viscosity grades

Comparison FactorsMixing Different Viscosity Grades
Viscosity EffectMixing different viscosity grades will result in a blended viscosity. The final viscosity will be influenced by the proportions of the different grades.
Temperature EffectsMixing different viscosity grades can alter the oil’s performance at different temperatures. The resulting blend may exhibit different flow characteristics and film thickness compared to individual viscosity grades.
Equipment SuitabilityMixing viscosity grades outside the manufacturer’s recommendations may affect the equipment’s performance. It’s crucial to ensure the blended viscosity falls within the acceptable range specified by the equipment manufacturer.
Operating ConditionsConsider the specific operating conditions when mixing viscosity grades. Higher viscosity oils provide better film strength and load-carrying capacity, while lower viscosity oils offer improved flow and energy efficiency.
Additive CompatibilityPay attention to the compatibility of additives present in different viscosity grades. Mixing oils with conflicting additive packages may impact performance or cause chemical reactions.
Testing and MonitoringPerform appropriate tests, such as viscosity measurements, to ensure the blended viscosity meets the desired specifications. Regular oil analysis can help monitor the performance and condition of the mixed viscosity grades.
Expert ConsultationWhen unsure or dealing with critical systems, consult with a lubricant specialist or the equipment manufacturer for guidance on mixing viscosity grades and any potential implications.

While it may be possible to mix ISO 32 and ISO 46 hydraulic oils, it is essential to be aware of the potential consequences that may arise from doing so.

Can You Mix 32 and 46 Hydraulic Oil

Performance issues

Mixing hydraulic oils with different viscosity grades can affect the system’s overall performance. The hydraulic pump may experience increased resistance due to the differing viscosities, leading to reduced efficiency and power output. Consequently, the system may operate less optimally, resulting in decreased productivity and potential equipment malfunctions.

Increased wear and tear

The differences in viscosity between ISO 32 and ISO 46 oils can impact the lubrication properties of the mixture. Inadequate lubrication can lead to increased wear and tear on critical components within the hydraulic system, such as pumps, valves, and cylinders. Over time, this can result in premature component failure and costly repairs.

Potential damage to the hydraulic system

In some cases, mixing hydraulic oils with significantly different viscosities can create a blend that is outside the acceptable range for the system.

This can lead to increased stress on the hydraulic components, potentially causing leaks, overheating, or even catastrophic system failure. It is crucial to exercise caution when considering oil mixtures to avoid damaging the hydraulic system.

Best practices for maintaining hydraulic systems

To ensure the longevity and optimal performance of hydraulic systems, it is recommended to follow these best practices:

Regular oil analysis

Performing regular oil analysis can provide valuable insights into the condition of the hydraulic oil and the system. This helps identify potential issues before they escalate and allows for timely corrective measures to be taken. Oil analysis can also determine the presence of contaminants or signs of oil degradation.

Flushing the system

If there is a need to switch hydraulic oils or if contamination is suspected, flushing the system is a crucial step. Flushing involves removing the old oil, cleaning the system thoroughly, and replacing it with fresh oil. This process helps eliminate any residue or contaminants that may negatively impact system performance.

Consulting equipment manufacturer guidelines

To ensure the appropriate hydraulic oil is used, it is advisable to consult the equipment manufacturer’s guidelines. They often provide specific recommendations regarding viscosity grades and other important considerations. Following these guidelines helps mitigate the risks associated with using incompatible or incorrectly mixed hydraulic oils.

Useful Tips for Mixing 32 and 46 Hydraulic Oil

CompatibilityMixing 32 and 46 hydraulic oil is generally compatible, but it’s important to consult the equipment manufacturer’s recommendations or the hydraulic system manual to ensure compatibility.
ViscosityMixing oils of different viscosities can result in an intermediate viscosity. The resulting viscosity will depend on the ratio of the oils mixed.
PerformanceMixing different oils may affect the overall performance of the hydraulic system. It can lead to changes in operating characteristics, such as reduced or enhanced performance, depending on the specific application.
AdditivesHydraulic oils often contain additives that provide specific properties. Mixing oils with different additive packages can result in unpredictable behavior or neutralize certain additive effects.
System FlushIf switching from one oil type to another, it’s generally recommended to flush the hydraulic system thoroughly to remove any residue or contaminants before introducing the new oil.
Manufacturer’s RecommendationIt’s crucial to follow the equipment manufacturer’s recommendations regarding hydraulic oil type and viscosity. Mixing oils should only be considered if explicitly approved by the manufacturer.
Expert ConsultationWhen in doubt or dealing with complex systems, it’s advisable to consult with hydraulic experts or professionals who can provide guidance tailored to your specific situation.

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Can I mix ISO 32 and ISO 46 hydraulic oils in an emergency situation?

In emergency situations where immediate access to the correct hydraulic oil is not possible, mixing ISO 32 and ISO 46 hydraulic oils may be a temporary solution. However, it is important to replace the mixture with the recommended oil as soon as possible to avoid potential damage to the system.

Are there any compatibility issues when mixing ISO 32 and ISO 46 hydraulic oils?

Compatibility issues may arise when mixing hydraulic oils with different viscosities, especially if the additives are incompatible. It is crucial to consult the manufacturer’s recommendations or seek professional advice before attempting such a mixture.

Can I mix hydraulic oils with other viscosity grades?

While it is generally not recommended, there may be situations where mixing hydraulic oils with similar viscosity grades is permissible. However, it is important to consider the compatibility of additives and the potential impact on system performance before doing so.

What should I do if I accidentally mix ISO 32 and ISO 46 hydraulic oils?

If you accidentally mix ISO 32 and ISO 46 hydraulic oils and it is not within the manufacturer’s recommended specifications, it is best to drain and flush the system as soon as possible. Replace the mixture with the correct hydraulic oil to prevent potential damage or performance issues.

Can mixing hydraulic oils improve system performance?

Mixing hydraulic oils is not intended to improve system performance. It is recommended to use the hydraulic oil specified by the equipment manufacturer to ensure optimal performance and longevity of the hydraulic system.


Mixing ISO 32 and ISO 46 hydraulic oils should generally be avoided unless specific circumstances warrant it.

While it may be possible to blend different viscosity grades, doing so can result in performance issues, increased wear and tear, and potential damage to the hydraulic system. Adhering to best practices, such as regular oil analysis, proper flushing procedures, and consulting manufacturer guidelines, is crucial for maintaining hydraulic systems’ optimal performance and longevity.