Qishanr QSL-PAG68 is a fully synthetic polyalkylene glycol (PAG) refrigeration lubricant engineered for compressors operating on HFC, HFO, and CO2 refrigerants. It is formulated around an ISO VG 68 base stock with a viscosity index of 209 — a figure that puts it well above conventional naphthenic mineral refrigeration oils and into the territory where film strength holds up under the thermal and mechanical stress of modern high-side-floating systems.
The additive package targets three things that kill compressors in the field: acid formation from refrigerant breakdown, varnish deposition on discharge valves, and viscosity collapse from refrigerant dilution. The result is a lubricant that stays in grade across wide temperature swings and keeps discharge temperatures manageable in flooded screw and scroll compressors running near the edge of their operating envelopes.
Mineral oils and alkylbenzene lubricants separate from HFC and HFO refrigerants — they simply do not miscibilise well enough to return to the compressor sump reliably. PAG oils solve this by maintaining controlled miscibility across the full evaporator temperature range, so the oil circulates with the refrigerant and comes back rather than pooling in the evaporator or suction line. For CO2 transcritical systems in particular, the high discharge pressures and temperatures demand a lubricant that resists thermal degradation; QSL-PAG68 was designed with those conditions in mind from the start. For a broader comparison of lubricant chemistries, see our guide to POE oil vs mineral oil for refrigeration systems.
The 8,000–15,000-hour service interval is not a marketing number. It comes from a testing programme built around the GB/T series of Chinese national standards, combined with multi-year field data from commercial refrigeration installations in China and Southeast Asia.
We ran an accelerated thermal-oxidative aging trial modelled on the sealed-tube stability test framework described in GB/T 31400 (modified for synthetic PAG chemistry). The protocol worked as follows:
Separately, a shear-stability test was conducted per GB/T 0103 (KRL tapered roller bearing rig, 20-hour run at 60°C). Viscosity loss was measured at less than 2%, confirming the polymer architecture resists mechanical shear — a common failure mode in screw compressor applications where the oil film is repeatedly worked between the rotors.
We monitored twelve commercial refrigeration systems across supermarket rack installations and cold-storage warehouses in Guangdong and Zhejiang provinces over a cumulative 210,000 compressor-hours. The systems spanned Bitzer and Hanbell semi-hermetic reciprocating compressors, Hanbell screw compressors, and Danfoss scroll compressors — all running R-404A, R-407F, or R-744 (CO2). Oil samples were pulled quarterly and analysed for TAN, viscosity, water content (Karl Fischer, GB/T 11133), and elemental spectroscopy (ICP-OES) to detect wear metals.
Across all twelve sites, TAN remained below 0.15 mg KOH/g through 10,000 hours of operation on average. The earliest TAN excursion reaching 0.3 mg KOH/g occurred at 8,200 hours in a flooded screw compressor operating in a high-ambient (38°C condenser inlet) fish-freezing cold store — which is exactly why the lower bound of the recommended interval sits at 8,000 hours. The cleanest-running systems, reciprocating units in air-conditioned machine rooms with stable load profiles, showed TAN values under 0.1 mg KOH/g at 15,000 hours.
For reference, naphthenic mineral refrigeration oils in the same compressor types typically show TAN values exceeding 0.3 mg KOH/g between 2,000 and 4,000 hours under comparable operating conditions. Compared to conventional POE and mineral refrigeration lubricants, the PAG chemistry resists oxidative and hydrolytic breakdown better — fewer acidic by-products, less sludge, less varnish. Extending the drain interval from 3,000 hours to 10,000 hours reduces annual oil consumption by roughly 70% and cuts the labour and downtime cost of oil changes by a similar margin.
The interval is a guideline, not a guarantee. We recommend pulling an oil sample at 4,000 hours for baseline TAN, then sampling every 2,000 hours thereafter. Change the oil when TAN rises by 0.3 mg KOH/g above the fresh-oil value, or when viscosity drifts outside ±15% of the nominal ISO VG 68 range. For systems with high discharge temperatures (above 110°C measured 150 mm from the discharge port), sample every 1,000 hours — the Arrhenius math is unforgiving at the high end.
| Property | Value | Test Method |
|---|---|---|
| Official product name | QISHANR QSL-PAG68 — PAG synthetic refrigeration compressor oil, published by QishanrLubricants | Match the grade and pack size on the existing container or service record. |
| Manufacturer | Guangzhou Qishanr Technologies Co., Ltd. (QISHANR brand, Foshan, China) | We blend this grade at our own plant. |
| Country of origin | Foshan, Guangdong, China (our own manufacture) | State the required pack size and destination on the enquiry. |
| Oil Type | Polyalkylene Glycol (PAG) Synthetic | — |
| ISO Viscosity Grade | ISO VG 68 | ISO 3448 |
| Kinematic Viscosity @ 40°C | 71.5 cSt | GB/T 265 |
| Kinematic Viscosity @ 100°C | 13.9 mm²/s | GB/T 265 |
| Viscosity Index | 209 | GB/T 1995 |
| Density @ 20°C | 1,020 kg/m³ | GB/T 1884 |
| Flash Point (COC) | 220°C | GB/T 3536 |
| Pour Point | -45°C | GB/T 3535 |
| Total Acid Number (fresh oil) | < 0.05 mg KOH/g | GB/T 7304 |
| Water Content (fresh oil) | < 50 ppm | GB/T 11133 |
| Copper Corrosion (3h @ 100°C) | 1a | GB/T 5096 |
| Available Capacities | 1 L / 5 L / 10 L / 20 L / 200 L | — |
QSL-PAG68 is recommended for the following compressor types across automotive, commercial, and industrial refrigeration and air-conditioning applications:
Note on elastomer compatibility: PAG oils are hygroscopic and may not be compatible with certain seal and gasket materials commonly used with mineral oils — particularly natural rubber (NR), nitrile rubber (NBR) below certain acrylonitrile content thresholds, and some epoxy-based coatings. EPDM, HNBR, and PTFE-based seals are generally compatible. Always consult the compressor manufacturer's lubricant specification before switching oil types. The complete guide to refrigeration oil compatibility with HFC refrigerants covers material compatibility in more detail.
QSL-PAG68 is miscible with the following refrigerant families:
Not recommended for: CFCs (R-12, R-502) or HCFCs (R-22) — these refrigerants are better served by mineral or alkylbenzene oils and, in any case, are being phased out under the Montreal Protocol and Kigali Amendment. QSL-PAG68 is also not suitable for ammonia (R-717) systems, which require a completely different lubricant chemistry.
PAG oils absorb moisture from ambient air. Keep containers sealed until use. Once opened, minimise exposure to humid air — ideally, use a nitrogen blanket or desiccant breather on bulk storage containers. Store between 5°C and 40°C in a dry, covered area. Shelf life in unopened original containers is 36 months from the date of manufacture. Do not mix QSL-PAG68 with mineral oils or POE lubricants — residual mineral oil concentrations above 1% by volume can cause additive dropout and impaired miscibility. If converting a system from mineral oil, a full system flush with the new PAG oil is recommended, and residual mineral content should be verified by oil analysis before the system is returned to service.
The Qishanr QSL-PAG68 PAG synthetic refrigeration oil offers an extended oil change interval of 8,000 to 15,000 hours, depending on operating conditions such as discharge temperature, system load, and refrigerant type. The lower bound (8,000h) applies to high-ambient, high-load flooded screw applications; the upper bound (15,000h) applies to clean-running reciprocating and scroll systems in climate-controlled machine rooms. The interval is determined by Total Acid Number (TAN) monitoring — change the oil when TAN rises by 0.3 mg KOH/g above the fresh-oil baseline.
QSL-PAG68 is fully compatible with HFC refrigerants (R-134a, R-404A, R-407C, R-410A, R-507A), HFO refrigerants (R-1234yf, R-1234ze), HFO/HFC blends (R-448A, R-449A, R-513A), and CO2 (R-744). It is not compatible with ammonia (R-717) or hydrocarbon refrigerants (R-290, R-600a), which require different lubricant chemistries.
PAG (polyalkylene glycol) and POE (polyol ester) are both synthetic refrigeration lubricants, but they differ in key properties. PAG oil has a higher viscosity index (209 vs. typical POE 120-150), better lubricity under boundary conditions, and superior solubility with CO2 refrigerant — making it the preferred choice for transcritical CO2 systems. POE oil offers better miscibility with HFC refrigerants across the full temperature range and is less hygroscopic. Both require sealed-container handling, but PAG is notably more moisture-absorbent and demands stricter service discipline. For a side-by-side spec comparison of POE options, see our QSL-68H vs Emkarate RL68H POE cross-reference guide.
Yes. QSL-PAG68 is specifically formulated for CO2 (R-744) compatibility, offering excellent solubility and thermal stability at the high discharge temperatures (up to 140°C) and pressures typical of transcritical CO2 booster systems. The high viscosity index (VI 209) ensures adequate bearing film strength even under the extreme conditions of CO2 transcritical operation. PAG is one of the few lubricant chemistries that performs reliably across all three CO2 refrigeration architectures: subcritical cascade, transcritical booster, and secondary-loop systems.
For technical data sheets, pricing, or sample requests, contact the Qishanr technical team.
The viscosity class quoted on this page follows ISO 3448, and the compressor-oil family classification follows ISO 6743-3. The typical values in the specification table are our own batch-tested figures, measured to the GB/T methods named in the table.
This oil is manufactured and supplied by Guangzhou Qishanr Technologies Co., Ltd., trading as the brand QISHANR. The company is based in Foshan, Guangdong, adjacent to Guangzhou Port, and has been producing lubricants for more than 10 years from its own blending plant. That plant runs at an annual capacity of 6,000 tonnes, which is what allows us to hold stock on the grades we list and quote firm lead times rather than promising on behalf of a third party.
Refrigeration oils are the core of the business, but they are not the whole plant. The same lines produce general industrial lubricants, so a mixed enquiry that covers both refrigeration oils and ordinary industrial grades can be quoted, packed and shipped together instead of being split across suppliers.
This is not the full range. Specialised ester base oils and lubricant additives are produced in-house as well, which is the reason the synthetic ester grades can be specified to a target rather than bought off a shelf. If the grade you need is not listed above, send the specification or the product you are replacing and we will confirm whether we produce it.
Long-term partners get pricing that reflects a stable manufacturing base rather than a trading margin, and the same technical contact stays with the account from grade selection through to repeat orders.
Original publication. The product data, specifications and application notes published on this page for PAG Refrigeration Oil ISO VG68 | Qishanr QSL-PAG68 Synthetic Compressor Lubricant for HFC/HFO/CO2 were originally published by QishanrLubricants on 2026-06-12 at qishanrlubricants.com. © 2026 QishanrLubricants. All rights reserved.
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