01/11/2026 by Thomas Clark
To perform at optimum and keep their components protected and in good working order, hard-working refrigeration compressors require a supply of high-quality lubricants.
These solutions must also be compatible with the refrigerants used in systems to ensure they can circulate properly and return to the compressor.
In this in-depth article, we’ll take a comprehensive look at Solest 170, a cutting-edge refrigeration compressor oil, and explore its uses, suitable alternatives, the refrigerants it is miscible with and more.
What is Solest 170?
Originally developed by the Lubrizol Corporation’s CPI Fluid Engineering, Solest 170 is a product in the Solest portfolio.
A full-synthetic polyol ester (POE) compressor oil specifically designed for refrigeration, it takes its name from its ISO viscosity grade of 170. This gives it a minimum viscosity of 153 centistokes at 40°C, a maximum viscosity of 187 centistokes at 40°C and a midpoint viscosity of 170 centistokes at 40°C.
Additionally, it is specifically engineered for high-temperature stability during operations and has a flash point of 265°C and a pour point of -22°C
What is Solest 170 used for?
An advanced refrigeration compressor oil, Solest 170 is used to lubricate heavy-duty compressors. It supplies bearing protection and high film strength for a range of reciprocating and screw compressors, like largescale industrial screw compressor systems.
It is employed when an oil is required that can work with modern refrigerants, and it effectively protects systems and their components against corrosion and wear. It creates a protective barrier on aluminium and steel parts, preventing rust and metal-to-metal friction while flushing contaminants.
It is also used to maintain thermal stability and effectively resists breakdown during wide temperature swings, helping to extend compressor lifespan and enhance overall energy efficiency.
What types of refrigeration and compressor applications is it designed for?
As a synthetic polyol ester (POE) compressor lubricant with a high viscosity, Solest has been expressly formulated for use in both industrial and commercial air conditioning and refrigeration systems.
While Solest 170 is approved for centrifugal, reciprocating and screw compressors, it is not recommended or listed for scroll compressors.
Which refrigerants is Solest 170 compatible with?
Solest 170 is engineered to work with modern refrigerants in use today, including low global warming potential (GWP) and hydrofluoroolefins (HFO) refrigerants, as well as hydrofluorocarbon (HFC) and hydrochlorofluorocarbon (HCFC) refrigerants.
What is the equivalent of Solest 170?
Listed equivalents for Solest 170 include Bitzer BSE 170, BVA RPOE 170 and RL170H of the Nu-Calgon equivalent line.
Can another POE 170 oil be used instead of Solest 170?
While another POE 170 oil can be employed instead of Solest 170, this is only the case if it matches the precise ISO 170 viscosity grade and is original equipment manufacturer (OEM) approved for the specific refrigerant in use and compressor type. Simply matching the viscosity of a POE oil alone does not make it necessarily a suitable replacement.
What is the difference between Solest 120 and Solest 170?
The key difference between CPI Fluid Engineering’s Solest 170 and Solest 120 is their viscosity grade.
This important property changes the strength of the fluid film they produce, their flow properties and their approved compressor compatibility.
Can Solest 170 be mixed with another refrigeration oil?
Solest 170 should not generally be mixed with mismatched grades or other types of refrigeration oil. For example, mixing POE and polyalkylene glycol (PAG) compressor oils can ruin chemical stability and damage compressor bearings.
Mixing unvalidated oils can not only degrade performance, but also void machinery warranties.
Does the existing lubricant need to be drained or flushed before switching products?
In most cases, existing refrigeration lubricants require draining, and often flushing, before changing products. Mixing incompatible compressor oils can cause chemical reactions, poor oil return, sludge formation and even compressor failure.
Before attempting to substitute an equivalent compressor oil, or mix two different oils, system operators should always contact an expert for advice, like the product manufacturer or an experienced lubricant supplier.
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