By the QISHANR Technical & Supply Team · Published 30 September 2026
Oil selection case · BITZER BSE32 (POE, 32 cSt) · 4CES-6Y reciprocating unit on R404A
This is our record of a service fill that turned into a grade confirmation, and of the six months that followed. BITZER BSE32 is a polyol ester (POE) refrigeration oil at 32 cSt at 40 °C, the grade BITZER documents for reciprocating compressors on HFC and HFO refrigerants. We supply it as the original BITZER oil or as our own equivalent, Qishanr QSL-32H, with TDS, SDS and a batch COA.
| Item | Detail |
|---|---|
| Customer | A plant running a cold line (not named) |
| Unit | BITZER 4CES-6Y reciprocating compressor on R404A |
| Service need | A service fill — the plant was down to half a can of the old oil |
| Grade they nearly bought | BSE55, on the strength of a catalogue listing |
| Grade we confirmed | BITZER BSE32 — polyol ester, 32 cSt at 40 °C, oil group KD to DIN 51503-1 |
| Selection rule applied | BSE32 is documented for stationary systems up to 70 °C condensing; BSE55 applies above that limit |
| Moisture requirement | Below 50 ppm for a replacement or alternative oil |
| What we shipped | 5 L packs with the batch COA |
| Reported at six months | Clean oil return, no foaming, no varnish on the last teardown |
We asked for the plant's own account of the selection and of the six months that followed it. This is what came back, reproduced as written:
We were one wrong order away from a very expensive mistake. Our Bitzer 4CES-6Y reciprocating unit on R404A needed a service fill, and our usual supplier's catalogue showed BSE55 as 'the Bitzer oil' — we nearly bought a full case. When we sent QISHANR the compressor model, they came back and said: this unit takes BSE32, not BSE55. BSE55 is only for condensing temperatures above 70°C; in our operating range it would run too heavy and starve the bearings. They confirmed the POE grade, checked the moisture requirement (below 50 ppm for this system), and quoted the 5L packs with the batch COA. Six months later the unit has run flawlessly: clean oil return, no foaming, and the last teardown showed no varnish at all. In the end, the right oil cost us less than the wrong oil would have.
The catalogue was right about the brand and wrong about the grade. BSE55 is a BITZER oil, but it is not the grade this unit runs.
The distinction sits in the compressor type designation. BITZER documents BSE32 for reciprocating compressors whose designation carries a “Y” — 4CES-6Y is the case in point — on chlorine-free HFC and HFO refrigerants.
The limit is the condensing temperature. BSE32 is documented for stationary refrigeration and air conditioning with condensing temperatures up to 70 °C, and BSE55 is the grade BITZER states above that figure, for mobile refrigeration and air conditioning.
A polyol ester (POE) is a synthetic refrigeration oil built on ester base stocks, miscible with HFC and HFO refrigerants and hygroscopic by nature. The grade number is not a quality ranking: 55 cSt is not better than 32 cSt, it is heavier.
Heavier oil in a machine specified for 32 cSt raises drag and changes how much oil the pump moves through the bearings at part load and low ambient. The plant's words were that the unit would run too heavy and starve the bearings.
That is the price of a catalogue hierarchy: selecting on model, refrigerant and condensing temperature costs one email.
Two things decide whether a POE service fill is safe: the right grade and a dry oil. We confirm both before we quote.
Moisture is the requirement that catches buyers out. BITZER's own condition for any alternative oil is a documented moisture content below 50 ppm, and that is the figure this plant asked us to confirm.
Hydrolysis is the chemical breakdown of an ester oil by water, and it produces acids inside the circuit. A hygroscopic POE is therefore judged on water content and total acid number, not on appearance.
We quote the grade against the model and the refrigerant, and ship the batch COA so the water content of the delivered batch is on the record. Water content in this class is determined under ASTM D6304, the Karl Fischer method.
The physical figures we hold for BSE32 come from BITZER's own documents: 32 cSt at 40 °C measured per DIN EN ISO 3104, the European equivalent of ASTM D445, a pour point of −57 °C and a flash point of 247 °C.
Pour point is the cold end of the service fill. At −57 °C, measured under ASTM D97, the charge stays mobile well below any plant room this customer operates in.
One caution belongs in the quotation. A polyol ester and a mineral oil are not interchangeable without a proper changeover. Send us what is in the system and we will confirm the procedure first.
The plant reported on three signals, and all three are the ones a service fill should move.
Oil return is the oil that leaves the compressor with the discharge gas and finds its way back to the sump. Their report is that return stayed clean.
No foaming is the second signal. Foam in the sump usually means refrigerant or moisture is sitting in the oil rather than circulating, and a dry charge at the right viscosity does not do it.
The last teardown showed no varnish. Varnish is what a POE leaves behind when it runs hot or wet, and a clean valve plate at six months is the proof that neither happened.
The plant closed their own account with the sentence we would have written for them: the right oil cost less than the wrong oil would have.
We would rather confirm a grade than fill an order. Send the compressor model, the refrigerant and the current oil, and we answer with the grade, the changeover position and the documents.
On supply, we can ship the original BITZER oil or our own equivalent, Qishanr QSL-32H, made in the same 32 cSt POE class in our plant in Foshan, Guangdong. A site can standardise on either route.
On packaging, BSE32 leaves us in 5 L, 10 L and 20 L packs, with no fixed minimum order — it is confirmed per order against pack size and destination, which suits a single service fill as well as a store restock.
On documents, every shipment carries a technical data sheet, a safety data sheet and a batch certificate of analysis: the batch record a plant files against the job.
On terms, we quote any Incoterms 2020 rule — EXW, FOB, CFR, CIF, DDP and the rest — against the destination port, and accept T/T, L/C and PayPal. Private-label supply is available on quotation.
We will also confirm the equivalent grade for the other compressors on a site, so a plant can consolidate its oil store instead of holding four part-used cans.
The figures we quote for this grade, with the source behind each one.
| Parameter | Value | Source |
|---|---|---|
| Product | BITZER BSE32 | — |
| Base oil | Polyol ester (POE) | — |
| Oil group | KD — the polyol ester group | DIN 51503-1 |
| Viscosity grade | 32 cSt at 40 °C — inside the ISO VG 32 band, 28.8–35.2 cSt | ISO 3448 |
| Kinematic viscosity at 40 °C | 32 cSt | DIN EN ISO 3104 |
| Kinematic viscosity at 20 °C | 74 cSt | DIN EN ISO 3104 |
| Flash point | 247 °C | BITZER KT-510-6 §4.1 |
| Pour point | −57 °C | BITZER KT-510-6 §4.1 |
| Density at −30 °C | 1.041 g/ml | BITZER ST-500-9 Tab.10 |
| Density at 100 °C | 0.942 g/ml | BITZER ST-500-9 Tab.10 |
| Refrigerants | R134a, R404A, R407C, R507A, R1234yf, R513A and other HFC / HFO blends | — |
| Compressors | BITZER reciprocating units with a “Y” designation, such as 4CES-6Y | — |
| Condensing temperature limit | Up to 70 °C — above that limit the grade is BSE55 | BITZER |
| Moisture requirement for an alternative oil | Documented below 50 ppm | BITZER |
| Supplied as | The original BITZER oil, or the Qishanr QSL-32H equivalent we manufacture in Foshan | — |
| Pack sizes | 5 L, 10 L and 20 L — minimum order confirmed per order | — |
| Documents | TDS, SDS and batch COA | — |
Fig. 1 — The 70 °C condensing temperature boundary that separates the two grades, and where this unit sits relative to it.
A: Yes. BSE32 is the grade BITZER documents for reciprocating compressors with a “Y” designation on HFC and HFO refrigerants, up to 70 °C condensing temperature. Above that figure the grade is BSE55.
A: Both. We supply the original BITZER oil and we manufacture the equivalent grade, Qishanr QSL-32H, in the same 32 cSt POE class in our Foshan plant. Either route comes with the same document set.
A: BITZER's requirement for an alternative oil is a documented moisture content below 50 ppm. The batch COA we ship records the water content of the delivered batch, measured under ASTM D6304.
A: 5 L, 10 L and 20 L packs, with a technical data sheet, a safety data sheet and a batch certificate of analysis. There is no fixed minimum order on this grade; it is confirmed per order.
A: Then it belongs in the BSE55 band. Send us the model, the refrigerant and the duty and we will confirm the grade rather than quote whatever is already on the shelf.
Confirming a BITZER oil grade before you order? Send the compressor model, the refrigerant and the oil currently in the system — we come back with the grade, the moisture requirement and the batch documents.
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