API Gear Lubrication Classification

AXLE & MANUAL TRANSMISSION LUBRICANTS (SAE J308)
Classification Type Typical Application
GL-1* Straight mineral oil. Some automotive manual transmissions under mild service.
GL-2* Usually contains fatty material. Worm drives and some industrial gearboxes.
GL-3* Contains mild EP additives. Manual transmissions and spiral bevel final drives under moderate service conditions.
GL-4* Contains EP additives. Equivalent to MIL-L-2105. Manual transmissions and transaxles, spiral bevel and hypoid gears in normal service without shock loading.
GL-5 Contains higher concentration of EP additives. Equivalent to MIL-L-2105 B/C/D. Hypoid and all other types of gears in severest service including shock loading. Primary field service recommendation for most passenger cars and trucks. Also may be used in manual transmissions.
GL-6* Obsolete. Hypoid gears with very high pinion offset.
MT-1 Protection against the combination of thermal degradation, component wear and oil seal deterioration. May or may not contain EP additives. Non-synchronised manual transmissions used in buses and heavy-duty trucks.

EP: Extreme Pressure.
* Obsolete.

NATIONAL LUBRICATING GREASE INSTITUTE GREASE CLASSIFICATION
Grade Number Worked Penetration @ 25°C
000 445 to 475
00 400 to 430
0 355 to 385
1 310 to 340
2 265 to 295
3 220 to 250
4 175 to 205
5 130 to 160
6 85 to 115