Quick answer: Solest is one polyol ester chemistry supplied in ten viscosity classes from 22 to 370 cSt at 40 °C. LT-32 measures 30.7 cSt, Solest 68 measures 66.3 cSt and Solest 170 measures 175.2 cSt at the same temperature. The compressor type settles the choice before viscosity does, because the published application matrix stops rotary and residential reciprocating duty at the 68 class, stops scroll duty at 120, and starts screw compressors at the 46 class. Pour point then fixes the cold end of the working window, at -54 °C for LT-32, -43 °C for Solest 68 and -22 °C for Solest 170.
Solest is a polyol ester (POE) refrigeration lubricant range from CPI Fluid Engineering, which now sits inside Lubrizol's refrigeration portfolio alongside the Emkarate and Icematic names. The manufacturer lists the range for HFC, HCFC and HFO refrigerants and for reciprocating, rotary, screw, centrifugal and scroll compressors. Every figure below comes from the manufacturer's published data for that grade.
The chemistry is the reason the range exists for HFC duty. Mineral oil does not mix with HFC refrigerants, so it stays in the sump and the evaporator loses its oil return path. A polyol ester has a controlled level of miscibility with HFC gases, so the mixture that leaves the compressor travels back with the refrigerant. Miscibility also thins the oil that circulates, so the class on the drum only opens the selection.
Ten classes sit in the range: 22, 31-HE, LT-32, 46, 68, 120, 170, 180, 220 and 370. Each one is the same base chemistry at a different viscosity, so a fleet can run one product type across several machines and still match the class each compressor asks for.
| Property (method) | Solest LT-32 | Solest 68 | Solest 170 |
|---|---|---|---|
| ISO viscosity class | 32 | 68 | 170 |
| Viscosity at 40 °C (ASTM D445) | 30.7 cSt | 66.3 cSt | 175.2 cSt |
| Viscosity at 100 °C (ASTM D445) | 5.4 cSt | 8.9 cSt | 16.5 cSt |
| Viscosity index (ASTM D2270) | 110 | 108 | 93 |
| Pour point (ASTM D97) | -54 °C | -43 °C | -22 °C |
| Flash point (ASTM D92) | 248 °C | 263 °C | 265 °C |
The three classes are 5.7 times apart at 40 °C, and the gap narrows as the oil heats: at 100 °C the spread is 5.4 to 16.5 cSt. The viscosity index explains part of that, and it runs the other way to the class, from 110 in LT-32 down to 93 in Solest 170. The heavier oil holds a thicker film in the bearings, and it loses proportionally more of that film as the temperature climbs.
Pour point spreads wider than anything else in the table: 32 degrees separate LT-32 from Solest 170, against 11 degrees between LT-32 and Solest 68. That figure decides which circuits each class can serve, and it is the one to check first when a compressor runs cold.
Flash point moves least. There are 17 degrees between the three, so the discharge side does not separate them. For the two heavier classes the sheets also publish the fire point, 293 °C for Solest 68 and 287 °C for Solest 170, plus density at 15 °C, 0.9552 and 0.9516 g/ml, and dielectric strength, 49.4 and 46.6 kV, the last of which matters in hermetic motors where the oil doubles as an insulator.
| Grade | Residential A/C recip. | Residential A/C rotary | Industrial centrifugal | Industrial recip. | Industrial screw | Industrial scroll |
|---|---|---|---|---|---|---|
| Solest 22 | Y | Y | Y | Y | Y | |
| Solest 31-HE | Y | Y | Y | Y | Y | |
| Solest LT-32 | Y | Y | Y | Y | Y | |
| Solest 46 | Y | Y | Y | Y | Y | Y |
| Solest 68 | Y | Y | Y | Y | Y | Y |
| Solest 120 | Y | Y | Y | Y | ||
| Solest 170 | Y | Y | Y | |||
| Solest 180 | Y | Y | Y | |||
| Solest 220 | Y | Y | Y | |||
| Solest 370 | Y | Y | Y |
Every limit in that grid rules out a class regardless of viscosity. Scroll compressors stop at 120. Rotary compressors stop at 68, and so does residential air conditioning reciprocating duty, which makes the 68 class the ceiling for the light end of the range. Screw compressors start at 46, so LT-32 is out for a screw machine however light the duty looks. Centrifugal and industrial reciprocating machines run the whole range from 22 to 370.
Read against the three grades in this article, the grid gives a short answer. LT-32 covers reciprocating, rotary, centrifugal and scroll duty. Solest 68 covers the same four plus screw. Solest 170 covers centrifugal, reciprocating and screw duty, and gives up both the residential classes and scroll.
The grade named in the compressor or unit documentation controls the decision. A specification that lists LT-32 and a specification that lists Solest 68 are not interchangeable answers to the same question, because the two differ in viscosity by more than a factor of two.
The matrix above is the second filter. A scroll machine takes any class up to 120, so LT-32 and Solest 68 are both open to it. A screw machine takes 46 and above, which closes LT-32 and opens Solest 68. A centrifugal machine takes everything in the range, so the class there is decided by the duty rather than by the machine type.
Pour point is the floor of the working window, and it spreads further across these three grades than any other property. LT-32 pours at -54 °C and suits low-temperature circuits where the oil has to keep moving through a cold suction line. Solest 68 at -43 °C covers the medium band. Solest 170 at -22 °C sits at the heavy and hot end, where film strength in the bearings matters more than a cold start.
A circuit runs on one class. Topping up a Solest 68 charge with LT-32 changes what circulates and lands between the two published data sets, so the film and the oil return both drift from the figures the machine was specified against. PVE and POE are separate families as well, and a machine built for one is not freely switched to the other without the compressor maker's changeover procedure.
Two routes come from one stock position. The original Solest LT-32 grade and the rest of the branded range are supplied as they arrive, and the same classes are also filled at our own blending plant in Foshan, Guangdong, as QSL-32H at ISO VG 32, QSL-68H at ISO VG 68 and QSL-100H at ISO VG 100, in your own branded container where the volume supports it. The 170 class is confirmed per order against the class and the pack size you need.
| Company | Guangzhou Qishanr Technologies Co., Ltd. |
| Brand | QISHANR |
| Location | Foshan, Guangdong, China. Nearest port, Guangzhou |
| Experience | More than ten years in refrigeration lubricants |
| Own plant | In-house blending, 6,000 tonnes a year |
| Approvals | Certified by major compressor manufacturers and by SGS |
| Documents | TDS, SDS and COA per batch; CE, CO, MSDS and transport identification report for export |
| OEM and ODM | Private-label artwork, pack design and material selection |
| Supply lines | POE, PAG, PVE, AB, GS, DRA and PAO series |
Send the compressor model, the refrigerant and the operating temperature, and we will confirm which of the classes above fits the machine, with the pricing and the lead time for that class.
Viscosity and pour point. LT-32 measures 30.7 cSt at 40 °C against 66.3 cSt for Solest 68, and pours at -54 °C against -43 °C. Both are listed for reciprocating, rotary, centrifugal and scroll duty; Solest 68 adds screw compressors and the 46 class below it.
Only where the compressor specification allows the heavier class. The two are more than a factor of two apart in viscosity and 11 degrees apart in pour point, so a charge of 68 where LT-32 was specified changes how the oil returns from a cold evaporator. Drain and refill with the specified grade rather than blending the two.
Solest 46 and every class above it in the range: 68, 120, 170, 180, 220 and 370. LT-32 and the two classes below it are not listed for screw duty.
Yes, the 120 class. Scroll duty is listed up to Solest 120, and the 170, 180, 220 and 370 classes are not listed for it.
-22 °C, measured to ASTM D97. That is the warmest pour point of the three grades here, and it places the class at the heavy-duty end where film strength in the bearings matters more than a cold start.
© 2026 Guangzhou Qishanr Technologies Co., Ltd. All rights reserved. This article, Which Solest Grade? LT-32, 68 and 170 Compared, was first published on October 16, 2026 at https://qishanrlubricants.com/blog-detail/which-solest-grade-lt-32-68-and-170-compared.
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