Can you mix hydraulic oils? The short answer is: sometimes, but it is not always recommended.
Two hydraulic oils can have the same viscosity grade, such as ISO VG 46, but that does not automatically mean they are compatible. Different hydraulic fluids can use different base oils and additive chemistries, which may react with each other and affect performance.
What should you check before mixing hydraulic oil?
Before mixing products, check:
- Manufacturer specifications and OEM requirements
- Base oil type
- Additive chemistry
- Hydraulic oil compatibility
- Existing oil condition and potential contamination
Mixing incompatible oils can reduce lubrication performance, affect seals and components, create deposits or cause other hydraulic system problems.
Changing Hydraulic Oil
If you are changing from one hydraulic oil to another, the safest approach is normally to drain the existing oil and assess whether the system requires flushing before introducing the new product.
Always follow the equipment manufacturer's specifications rather than choosing an oil based on viscosity alone.
Need help choosing the right hydraulic oil? Lube Line Distribution supplies hydraulic oils from leading manufacturers, including Shell Tellus and Fuchs. Contact us for advice on hydraulic fluid compatibility and the correct product for your application.
