What Is Industrial Gear Oil? Types, Labels and Typical Values

How does industrial gear oil protect gear teeth?

Industrial gear oil protects gear teeth in two ways: a pressurized oil film keeps the tooth flanks apart, and additives form a protective surface layer where the film is too thin. The film depends on viscosity, and viscosity depends on temperature. A lower oil temperature leads to a substantial increase of oil viscosity and a thicker lubricant film in the contact zone (Gear Solutions, 2013).

The film does not always carry the whole load. Lubricant film thickness calculations for typical gearbox applications show that even at oil temperatures as low as 40 °C, a gearbox can still operate under mixed or boundary lubrication, depending on the other operating conditions (Gear Solutions, 2013). In that regime, the formation of an additive reaction layer on the gear surfaces is vital to protect them against damage (Gear Solutions, 2013).

Contact stress explains why. In the FZG slow speed wear test at load stage 12, the gear contact sees a Hertzian pressure of 1,853 N/mm2 at 0.05 m/s (Gear Solutions, 2013). This is why load-carrying additives matter in heavily loaded drives. The oil also has to cool the mesh, release air and drop out water.

What is industrial gear oil made of?

Industrial gear oil is made of a base oil, mineral or synthetic, plus an additive package chosen for the gear type and duty. A typical heavy-duty product is formulated with mineral base oils and a multifunctional additive for enclosed drives with circulation or splash lubrication (Sinopec, accessed 2026). Synthetic versions use other base fluids: in DIN 51517-3 naming, CLP HC is typically a synthetic such as polyalphaolefin (PAO) or ester, and CLP PG a polyalkylene glycol (PAG) oil (Design World, 2018).

The additive package defines the type. ANSI/AGMA 9005-F16 recognizes three families (STLE TLT, 2024):

• Inhibited oils, with rust and oxidation inhibitors.

• Antiscuff oils, with additives for load-carrying capacity; AGMA encourages the term antiscuff over extreme pressure (EP).

• Compounded oils, which under the older AGMA 9005-D94 contained 3% to 10% fatty material for worm gears (STLE TLT, 2024).

ANSI/AGMA 9005-F16 includes rust, copper strip corrosion and foam tests (STLE TLT, 2024), so formulations also carry corrosion inhibitors and antifoam agents. For a gear oil, read the type on the data sheet, not just the base oil.

What do CKD, CLP and AGMA EP mean on industrial gear oil?

CKD, CLP and AGMA EP on industrial gear oil are performance labels from three standards systems: ISO, DIN and AGMA. Each says which additive class and minimum tests the oil meets, and none replaces the ISO viscosity grade, which appears next to it, as in CLP 220.

The label decoder below shows what each common enclosed gear oil label means and where it comes from.

The key row is CKD: it asks for the CKC properties plus higher temperature stability, which is why, in one maker's 2016 summary, its oxidation test runs at 121 °C instead of 95 °C (FUCHS, 2016). DIN 51517-3:2018-09 is the current CLP edition (DIN Media, accessed 2026), and ISO 12925-1:2024 covers the CKB, CKC, CKD and CKE categories among others (ISO, 2024). One data sheet can carry several labels: one antiscuff (EP) gear oil line is described as typically suitable where DIN 51517 Part 3, ISO 12925 Type 1 CKC and AGMA 9005-F16 are required (Petro-Canada, accessed 2026).

What are the typical properties of an ISO VG 220 industrial gear oil?

A typical ISO VG 220 industrial gear oil has a viscosity near 220 mm2/s at 40 °C, and published data for two antiscuff products show a viscosity index of 93 to 102 and an FZG fail load stage above 12 (Sinopec, accessed 2026; Petro-Canada, accessed 2026). ISO viscosity grades allow plus or minus 10% around the midpoint (Design World, 2018).

The table below compares published data for two antiscuff ISO VG 220 products with the AGMA limits, so you can judge a data sheet.

The pour point row shows why a grade alone is not enough: two ISO VG 220 antiscuff oils differ by 21 °C in pour point (Sinopec, accessed 2026; Petro-Canada, accessed 2026). Typical values on a data sheet are not guaranteed limits. Compare them with the limits that the gearbox maker or the named standard sets, and ask the supplier for the test method and conditions behind any number that decides your choice.

Why does industrial gear oil quality matter for gearbox life?

Industrial gear oil quality matters for gearbox life because the oil's additives and stability, not only its viscosity, decide whether gears and bearings survive mixed lubrication, water and heat. Gear damage is often caused by rolling bearing wear or fatigue, and the type, condition and quantity of lubricant have a main influence on bearing failures (Gear Solutions, 2013).

Water is a frequent threat. Water contamination is common in industrial gearsets from leaky oil coolers, frequent water washdowns and gearboxes breathing in humid conditions; with proper demulsibility, the water can be decanted after an overnight or weekend shutdown (STLE TLT, 2024). Oxidation is another: ANSI/AGMA 9005-F16 limits the viscosity increase of antiscuff oils in the ASTM D2893 aging test and sets minimum aging hours for inhibited oils under ASTM D943 (STLE TLT, 2024).

Low temperature service is a third case. Some additive types need a certain contact temperature to react with the surface, so gearboxes that run below full load or with frequent stops need oils proven to protect at lower oil temperatures (Gear Solutions, 2013). When you compare oils for a specific gearbox, Lubinpla can work from your own TDS, SDS and gearbox history and return one cited document for your review.

Related terms

• ISO viscosity grade (ISO VG): the viscosity class of an industrial oil at 40 °C (Design World, 2018).

• Antiscuff: the AGMA term for oils formerly called EP.

• FZG test: a gear rig test that rates scuffing load capacity by load stage.

• Demulsibility: how quickly an oil separates from water.

• Automotive gear oil: oil for vehicle axles and transmissions, graded by SAE J306 and API categories instead of ISO VG.