Introduction: RL170H selection for R134a screw compressors depends on measured 40°C viscosity, not on an ISO VG label.
170 cSt sits between ISO VG 150 and ISO VG 220, so R134a screw compressor selection has to use measured viscosity, not a grade label. In an OEM bill of materials, a line may call for ISO VG 150 or ISO VG 220 while the oil being offered measures 170 cSt at 40°C. That gap appears often in R134a screw compressor programs, and it is manageable when both numbers are compared the same way. Problems start when someone writes “VG 150 equivalent” on a purchase order because the number looks close, and the compressor ends up running on an oil film that was never matched to the specification. Getting the comparison right takes three steps: understanding what 170 cSt means in a screw compressor, reading the RL170H data as measured values, and matching the oil to what the compressor OEM approved.
ISO VG grades are printed as bands, not single values. At 40°C, ISO VG 150 covers 135 to 165 cSt and ISO VG 220 covers 198 to 242 cSt. A 170 cSt oil sits between them, so no standard ISO VG grade number applies. For a screw compressor, rotor sealing and bearing protection depend on the oil film the lubricant can hold at operating temperature, and film thickness tracks measured viscosity. Many commercial and industrial screw compressor OEMs approve oil by viscosity range or by a named product rather than by ISO grade for this reason. Refrigeration duty makes the measurement more important. In an R134a circuit, refrigerant dissolves into the POE oil, so the viscosity the bearings see is lower than the neat value on the data sheet. A 170 cSt oil in the drum becomes thinner in a hot sump under high pressure. That is why compressor OEMs and oil suppliers compare oils at 40°C before refrigerant dilution: it is the one value both sides quote the same way. POE is also the base fluid for R134a work because the oil and refrigerant remain miscible, which supports oil return from the evaporator.
The RL170H specification sheet gives six values worth mapping to your machine. At 40°C it measures 170 cSt, and at 100°C it measures 17.0 cSt, both by ASTM D445. Those two points set the slope of the oil’s thinning curve. Viscosity index is 107 by ASTM D2270, which describes how well the oil holds viscosity as temperature climbs through the discharge end and drops again at the evaporator. Pour point is -25°C by ASTM D97, flash point is 290°C by ASTM D92, and density is 0.968 g/ml by ASTM D1298, which helps when converting between weight and volume for bulk planning. Together, these values describe an oil that still flows at cold evaporator conditions and keeps a film at screw rotor temperatures. The flash point matters because screw compressors concentrate heat at the discharge end; the 290°C open-cup flash point is part of that high-temperature profile. The -25°C pour point matters at the other end: in a cold-room circuit or winter startup, oil has to travel back to the compressor rather than sit as wax in the evaporator. Acid value and moisture content are not fully published for RL170H, so confirm both against the current TDS before releasing a purchase order. When the specification is written, it should carry 170 cSt as the 40°C value, not an ISO VG 150 or ISO VG 220 label.
A specification match comes down to four comparisons. Run them in order, because the first one decides whether the rest matter.
Once those four points are settled, the commercial side is straightforward. Send the compressor model, the OEM oil specification, and the refrigerant to your refrigeration oil supplier, and ask for the current TDS plus a sample in the packaging format you plan to order. A POE refrigeration oil manufacturer that publishes ASTM D445 data gives you a direct comparison instead of a grade-label guess. A refrigeration oil manufacturer that controls batch documentation can support the RFQ. For OEM programs, and for wholesale refrigeration oil or wholesale POE refrigeration oil orders, the 40-piece MOQ supports a pilot fill, and EXW, FOB, CFR, and CIF pricing with T/T or L/C payment lets you model landed cost against the brand currently specified.
170 cSt is a measurement, not a grade, and that single fact reshapes how oil gets specified for an R134a screw compressor. Match the 40°C value, check the temperature data against your duty cycle, confirm the packaging your line uses, then settle the commercial terms. RL170H from QISHANR Lubricants delivers 170 cSt at 40°C, 17.0 cSt at 100°C, a 107 viscosity index, a -25°C pour point, and a 290°C flash point, packed in 5L and 20L containers with a 40-piece minimum order. Share your compressor model and current oil specification, and ask for the current TDS together with pricing for the volumes you run.
A：It has no standard grade number because 170 cSt at 40°C falls between ISO VG 150 (135 to 165 cSt) and ISO VG 220 (198 to 242 cSt). That gap is normal for specialty POE refrigeration oils. Compare the 170 cSt value directly against the 40°C viscosity in your compressor specification or the oil currently approved for the machine.
A：A grade label is a band covering as much as 45 cSt, so it can hide a meaningful difference in film thickness. R134a also dissolves into POE oil and lowers the working viscosity inside the compressor, which makes the neat 40°C value the number OEM approvals are based on. Quoting 170 cSt keeps both sides of the comparison on the same scale.
A：Yes. RL170H is a synthetic polyol ester refrigeration oil for HFC systems with R134a named in its data, and it is suitable for screw, scroll, and reciprocating compressors. The 170 cSt viscosity, 107 viscosity index, 290°C flash point, and -25°C pour point fit commercial and industrial screw duty. Confirm acid value and moisture from the current TDS, and follow the compressor OEM for any refrigerant other than R134a.
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