The most extensively referenced industrial oil classification is the one established by ANSI/AGMA (American National Standard Institute/American Gear Manufacturers Association) that classifies industrial gear oils where gear oils are classified into four types as shown in the following table :

① R&O gear oil is formulated to contain, as additives, rust inhibitor and oxidation inhibitor and is distributed as multi-purpose oil for various applications.  
② EP gear oil contains extreme pressure agents such as S-P additive and it is used in larger quantity than any other gear oil type. In addition,  
③ Compound type and ④ synthetic gear oil are used for special applications.​ 

 

[AGMA Gear Oil Classification for Enclosed Gear Units for Industrial Applications]

Gear Oil Type	Formulation	Operating Temperature Limit
R&O Type	Mineral oil containing oxidation inhibitor and rust inhibitor as additives	200℉(93℃)이하
EP Type	Mineral oil containing extreme pressure agent as additive. Gear oil for enclosed gear unit uses naphthenic acid or S-P based extreme pressure agent.	160(71℃)~200℉이하
Compound Type	Mineral oil containing 3~10% of fatty oil or synthetic fatty acid (generally used for worm gears)	160(71℃)~200℉이하
Synthetic Type	Polyol Ester, Poly Glycol, and synthetic hydrocarbon-based synthetic oil (used for enclosed gear units designed for special operating conditions or worm gears)

 

 

[AGMA Gear Oil Classification for Semi-Enclosed Gear Units and Open Gears for Industrial Applications]

Gear Oil Type	Formulation
R&O Type	Mineral oil containing oxidation inhibitor and rust inhibitor as additives
EP Type	Mineral oil containing naphthenic acid or S-P based extreme pressure agent as additive.
Compound Type - 희석 Type	Straight mineral oil of high-viscosity grade or EP oil diluted with volatile non-flammable solvent (solvent-dilution type)

 

In gear lubrication, the most important performance property is viscosity and, depending on the gear configuration, number of gear teeth, operating conditions, etc.,

​gear oil of appropriate viscosity needs to be selected.  As for the viscosity classification of industrial gear oils, AGMA specifies it for high-viscosity grades, too. 

AGMA also adopted a viscosity number specifying kinematic viscosity from 37.8℃  to 98.9℃ as in open gear applications

 

ANSI/AGMA classification is used in general for viscosity classification of industrial gear oils. The following table shows the mapping between ISO viscosity classification and ANSI/AGMA viscosity classification: 

 

Vis.mm²/s(40℃)	ISO VG	AGMA
		R&O	EP	Synthetic
28.8~35.2	32	0	-	0S
41.4~50.6	46	1	-	1S
61.2~74.8	68 2	2	2EP	2S
90.0~110	100	3	3EP	3S
135~165	150	4	4EP	4S
198~242	220	5	5EP	5S
288~352	320	6	6EP	6S
414~506	460	7,7Comp	7EP	7S
612~748	680	8,8Comp	8EP	8S
900~1100	1000	8A,8AComp	8AEP	-
1350~1650	1500	9	9EP	9S
2880~3520	-	10	10EP	10S
4140~5060	-	11	11EP	11S
6120~7480	-	12	12EP	12S
190~220mm²/s @100℃	-	13	13EP	13S