Two Years in Service: A Returning Customer's Report on QSL-32H

By Qishanr Technical Team · Published 17 September 2026
Customer field report · QSL-32H · over two years in service

The Case at a Glance

What the Customer Reported

The source for this case is one line from a customer we have supplied for years, quoted in full:

“Has held up in systems for over 2 years with no signs of breakdown.”

Why Two Years Is a Different Test From a First Oil Change

A lubricant can look excellent for a few weeks and still be the wrong choice. Failure mechanisms do not all run at the same speed: some announce themselves on the first day, others need months of heat, moisture and cycling before they are visible at all. That is why the length of the run matters as much as the result.

What shows up early

Most of the problems that end a changeover in the first weeks are not slow at all. A grade that is wrong for the compressor, an oil that has picked up moisture during a wet changeover, mineral oil left behind in a circuit that now runs on ester, contamination carried in with the charge — these make themselves known in days or weeks, through oil return, capacity, noise or a discoloured sample.

What only shows up late

The slow mechanisms are the ones a long run is really testing:

• Thermal and oxidative ageing of the oil itself, driven by discharge temperature and by the number of hot-cold cycles the circuit sees.
• Acid build-up from moisture working on an ester, which is the route to varnish and to the deposits that eventually block fine passages.
• Additive depletion — the point where a stable oil starts to lose the margin that made it stable.
• Progressive oil-return loss, which rarely fails suddenly: it accumulates in the evaporator and shows up as declining performance long before it shows up as a breakdown.

Two years of ordinary operation gives every one of those mechanisms time to appear. A report that says none of them has is therefore a much stronger statement about a lubricant than a clean sample taken after the first month.

What “No Signs of Breakdown” Is Checked Against

“No signs of breakdown” is a service statement rather than a laboratory number, and in a plant it is read from a set of observations that only mean something once they have been repeated across months:

1. The oil’s appearance at each service. Some colour drift is normal. The signals are oil that darkens faster than its own trend, a burnt note, cloudiness, or sediment in the bottom of the pail.
2. Acid value and moisture, where the site samples its oil. These are the two numbers that move first when an ester is slowly breaking down under heat and moisture.
3. Oil level and top-up volume. A steady top-up record is evidence the oil is staying in the circuit rather than quietly logging in the evaporator.
4. Oil return and compressor behaviour. Sump level and sight glass on a regular round, plus noise and discharge temperature held steady at comparable load.
5. Heat-transfer performance. Approach temperatures on the evaporator and condenser, compared at similar load. A slow upward drift is the classic sign of oil where it should not be, long before anything fails.
6. Filter and strainer condition at service. What the screens are catching tells you what the oil has been carrying through the circuit.
7. Nothing unusual in the maintenance log. The least dramatic item on the list, and the most persuasive one when it covers two years.

Read together, those seven observations are what a customer is really reporting when they say a lubricant has held up. None of them requires a laboratory to interpret, and all of them get more meaningful the longer the run has been.

The Chemistry That Makes a Long Run Possible

QSL-32H is a full synthetic polyol ester, and the properties printed on the tin are the ones that decide whether a fill survives two years or two months:

• Thermal stability. An ester base holds its structure at the discharge temperatures a working compressor produces, which is where ageing starts.
• Chemical stability. Resistance to the reaction that produces acids, and through them varnish and deposits.
• Miscibility with HFC refrigerants. Oil that mixes properly with the refrigerant travels around the circuit with it and comes back to the compressor, instead of accumulating in the evaporator.
• A pour point of −50 °C. Margin at the cold end, so the oil keeps moving on the coldest surface in the system.
• A viscosity index of 130. The film stays useful across the temperature range between a cold evaporator and a hot discharge, rather than thinning away where it is needed most.

What Still Ends a POE Run

A good ester is not indestructible, and two years of service is also two years of exposure to the three things that shorten it:

• Moisture. An ester absorbs water from air, and water plus heat plus ester is the route to acid and sludge. Keeping pails closed and circuits dry is what protects the whole run.
• Mineral oil left behind. Residue from a previous fill that does not mix with the refrigerant will migrate to the evaporator and stay there, regardless of how good the new oil is.
• Sustained high discharge temperature or permanent part load. Both push ageing and oil logging faster than the oil's own chemistry would.

A two-year run with none of these showing up is, in practice, a statement about the oil and the circuit together.

QSL-32H Reference Data

These are the QSL-32H reference values used across our refrigeration oil guides:

A Returning Customer, Two Years On

The one-line report came from a customer we already supply, and that changes what it is worth. A first-time buyer can only describe a first impression. A customer who has run the same oil through several service cycles, watched the same machines through more than two years, and still writes back with “no signs of breakdown” is reporting a settled result rather than an early one.

It is also the point where a lubricant stops being a purchase decision and becomes the default: the same grade arriving on the same terms, and a service log with no surprises in it. For anyone weighing grades, that is the record worth asking a supplier for — not a testimonial, but a horizon. Our two-month QSL-32H field observation shows the same product at its first checkpoint; this is what that checkpoint grows into.

How a Two-Year Run Is Kept Going

Nothing on this list is exotic, and that is the point — a long run is usually the result of ordinary discipline rather than exceptional circumstances:

1. Keep the circuit dry. Closed pails, dry charging practice and filter driers changed on schedule protect an ester better than any additive can.
2. Sample on a rhythm. Acid value and moisture at each service; the trend across visits tells you more than any single reading.
3. Watch oil return. Sump level, sight glass and approach temperatures at comparable load — the earliest signal of oil moving somewhere it should not.
4. Hold the operating envelope. Superheat, charge and discharge temperature inside the specified window, instead of permanently at its edge.
5. Record the batch. A batch reference on the service sheet lets a future sample be compared with the oil that was actually filled.

Who This Case Fits — and Where to Choose Differently

FAQ

What is QSL-32H?

A full synthetic ISO VG32 polyol ester lubricant for HFC refrigeration systems, supplied in 1 L to 200 L packaging. Its reference values are in the table above.

Can QSL-32H replace Emkarate RL32H or Bitzer BSE32?

Both are ISO VG32 ester oils, so the change matches on oil family and viscosity grade. Send the compressor documentation, the refrigerant and the oil charge, and we will confirm the grade against your build before you order.

How should I set my oil-change interval after a report like this?

Use the long run as evidence for the grade, and set the interval from your own sampling trend — acid value, moisture and appearance at each service. A dependable grade is a reason to sample with confidence, and to let the trend rather than the calendar decide the change.

What should I send with an enquiry?

The compressor type and model, the refrigerant, the oil charge per unit, the oil you are using now, the packaging you want, your destination, and any documents your inspection requires.