Separates
Keeps a film between moving metal parts, so they slide on oil instead of on each other.
Lubricating oil, matched to the machine
Refrigeration, compressor, gear, engine and insulating oils for your plant — chosen by oil type, grade and the maker's specification.
- Friction
- Low
- Bearing heat
- Normal
- Wear
- None
Gap drawn far larger than real: in a running bearing the thinnest film is only a few thousandths of a millimetre.
What the oil does
One fluid, four jobs at once
Cools
Carries heat away from bearings, gears and — in a screw compressor — from the air being compressed.
Cleans
Picks up wear particles and dirt and carries them to the filter instead of leaving them in the contact.
Seals & protects
Closes the tiny gaps between compressor rotors and coats steel against rust and acid.
Oil finder
Which oil goes in which machine
Pick a machine from your plant. The grade shown is the usual range — the nameplate and the maker's manual always have the final word.
Tap a machine to see its oil
Chiller compressors
Chillers service- Oil
- Refrigeration compressor oil
- Typical grade
- Scroll: usually ISO VG 32 · Screw: commonly ISO VG 68–220, some higher
- Check against
- The compressor maker's approved oil. The oil family follows the refrigerant — pick it below.
Refrigerant in the machine
Polyolester (POE)
HFC and HFO refrigerants do not mix well with mineral oil; POE lets the oil travel back to the compressor.
Watch for
- POE takes up moisture quickly once opened. Keep it in sealed metal cans and close them straight after use.
- Moisture in POE turns into acid: copper plating, worn bearings and, in the end, a burnt motor winding.
- After a motor burnout, test the oil for acid and fit burnout filter driers; change them until the acid test passes.
When to sample or change
Have the oil tested for acid and moisture at service visits. Change it on the result, after a burnout, or at the maker's interval.
Cold room & freezer compressors
Cold Storage service- Oil
- Refrigeration compressor oil
- Typical grade
- As on the compressor plate — low-temperature duty needs the maker's low-temperature oil
- Check against
- The compressor maker's approved oil. The oil family follows the refrigerant — pick it below.
Refrigerant in the machine
Polyolester (POE)
The usual oil for HFC and HFO cold rooms and blast freezers. Same moisture care as chillers.
Watch for
- Top up only with the oil already in the machine.
- Watch the oil level at the compressor sight glass: oil that does not come back starves the compressor.
When to sample or change
Have the oil tested when it darkens, when the compressor runs hot, and after any burnout.
Air compressors
Air Compressor service- Oil
- Air compressor oil — mineral or synthetic (PAO, ester, PAG)
- Typical grade
- Screw: ISO VG 46 is the most common (32–68) · Piston: heavier grades as the maker states
- Check against
- ISO 6743-3: L-DAH / DAJ for oil-flooded screw · DAA / DAB for piston compressors
Watch for
- In a screw compressor the oil also seals the gaps between rotors and housing, and carries away the heat of compression.
- Never mix PAG-based oil with mineral or PAO oil — they are not compatible.
- Food and beverage plants: use NSF H1 registered oil where it may touch the product.
- Rising oil carry-over in the air line usually means a saturated separator element; also check the oil level.
When to sample or change
By the hour meter: mineral oil commonly up to about 4,000 h or one year, long-life synthetics up to about 8,000 h — the maker's interval and the running temperature decide.
Cooling tower gear reducers
Cooling Towers service- Oil
- Gear oil approved by the reducer maker — synthetic, or turbine-type mineral oil
- Typical grade
- Set by the reducer manual and the season — commonly ISO VG 150–220
- Check against
- Many reducers must not get oils with EP or detergent additives — check the manual before buying.
Watch for
- Check the oil level with the fan stopped, after the oil has settled for a few minutes.
- Warm, wet air puts water in the oil through condensation — drain it off when you see it.
- Keep the breather vent clear.
When to sample or change
Turbine-type mineral oil: about every six months. The maker's synthetic gear oil lasts much longer — follow the reducer manual.
Diesel generators
Power & Electrical service- Oil
- Heavy-duty diesel engine oil
- Typical grade
- SAE 15W-40 is the usual grade
- Check against
- API CI-4 or CK-4, or the engine maker's own oil specification
Watch for
- A set that runs on light load for long hours lets fuel into the oil (wet stacking) — have the oil tested.
- A standby set ages its oil by time as well: change it at least once a year, even if the hour meter barely moved.
- Change the oil filter with every oil change.
When to sample or change
At the hours in the engine manual, or once a year if those hours are not reached.
Pumps, fans & AHU motors
HVAC service- Oil
- Bearing grease or bearing oil
- Typical grade
- Grease NLGI 2 (polyurea or lithium complex) · Oil-bath bearings ISO VG 46–100, most often 68
- Check against
- The grease named on the motor or pump plate
Watch for
- More grease is not better: an over-packed bearing runs hot and can push grease into the motor winding.
- Greases with different thickeners (lithium and polyurea, for example) may not be compatible — purge the old grease first.
When to sample or change
Re-grease by the quantity and interval on the motor or pump plate; check oil-bath bearings by level and colour.
Transformers
Power & Electrical service- Oil
- Mineral insulating oil
- Typical grade
- Judged by tests, not by a viscosity grade
- Check against
- New oil: IEC 60296 · Breakdown voltage: IEC 60156 · Moisture: IEC 60814 · Dissolved gases: IEC 60599
Watch for
- Its job is insulation and cooling — moisture and particles lower the breakdown voltage.
- Gases dissolved in the oil show developing faults, such as overheating or arcing, before they trip the transformer.
When to sample or change
Test breakdown voltage and moisture on a schedule; filter or replace the oil on the result.
Reading the grade
What the ISO VG number tells you
The number is the oil's thickness at 40 °C in mm²/s (cSt), with ±10 % allowed (ISO 3448). Each grade is about one and a half times the one before. The right one forms a film without wasting power.
ISO VG 100
90–110 mm²/s at 40 °C
Piston air compressors, pump oil-bath bearings
Oil analysis
An oil sample tells you what the machine will not
Viscosity is the first line on any oil report. Move the slider to see how a change from new oil is usually read.
Viscosity change from new oil0 %
Normal
Close to new oil — keep sampling on schedule.
A common rule of thumb in oil analysis; some machine makers allow more. The maker's limits come first.
Water
In refrigeration oil it feeds acid; in gear and bearing oil it rusts teeth and races.
Acid number
Rises as the oil oxidises or reacts with moisture. A steady climb means the oil is near the end of its life.
Wear metals
Iron points to gears, shafts and bearings. Copper alone often comes from a cooler; copper with tin, from a bronze part.
Particle count
Reported as an ISO 4406 code — the number of particles above 4, 6 and 14 µm. Dirt in the oil is wear waiting to happen.
Storage and handling
Good oil goes bad in the store, too
One oil, one machine
Top up with exactly what is in it. Label every can and pump with the oil it is used for.
Keep it sealed
Close containers right after use. POE and PAG oils take up moisture from humid air once opened.
Store drums under cover
Lay them on their side with the bungs at 3 and 9 o'clock, so rainwater cannot sit on the bungs and be drawn in.
Clean transfer
Use clean, dedicated pumps and containers. A dirty funnel can undo a new oil charge.
Record every change
Date, hours, oil and quantity on the machine log — it makes the next oil report readable.
Used oil to a recycler
Collect it in closed drums for a licensed collector — never into drains or soil.
Ordering
From nameplate to the right drum
- 1
Send the nameplate
Photo of the machine plate, the refrigerant and running hours — on WhatsApp is fine.
- 2
We match the oil
Oil family, grade and specification checked against the maker's requirement.
- 3
Delivered sealed
Sealed packs to your site, with the oil change done by our service team if you want it.
Questions
Asked before every oil order
Only when the oil family and the specification are the same — for example POE to POE of the same ISO grade. Mixing families (POE with mineral oil, PAG with anything else) is where most oil problems start. When in doubt, send us the nameplate and the label of the oil already in the machine.
No. A grade that is too heavy wastes power, runs hotter and reaches the bearings late on start-up; one that is too light cannot hold the film under load. Use the grade on the plate unless the maker recommends a change.
It is the oil's kinematic viscosity at 40 °C: VG 68 oil measures between 61.2 and 74.8 mm²/s (cSt). Each ISO 3448 grade is about one and a half times the one before.
No. SAE grades such as 15W-40 are a separate system for engine oils. Only rough equivalents exist, so never swap one for the other.
A clear photo of the machine nameplate, the refrigerant (for chillers and cold rooms), the running hours and, if you have it, the oil label. That is usually enough to match the oil type and grade to the maker's specification.
Not sure which oil your machine takes?
Send a photo of the nameplate. We will tell you the oil type and grade the maker asks for.