Synthetic Gear Lubricants are used in gearboxes operating at extreme temperature conditions and are recommended for use in applications where the component handles heavy loads but may not benefit from Extreme Pressure Additives. Extreme Pressure (EP) additives are not recommended in gearboxes where the corrosion of yellow metals is a concern, therefore, the increased performance characteristics of synthetic gear lubes can compensate for some of the lost performance accompanied with the lack of EP additives.
AGMA 2 oils are also classified as ISO VG 68 oils. AGMA 2 S oils have the same relative viscosity as AGMA 2 oils, however, they are marked to show they are Synthetic in formulation, which may or may not be interchangeable with mineral-based gear lubes. These oils have a midpoint kinematic viscosity of 68 mm2/s, also referred to as centistokes (cSt). The midpoint is derived by taking the average of both the minimum and maximum kinematic viscosities. In the case of ISO VG 68 oil (also AGMA 2 oil), those numbers are 61.2 cSt and 74.8 cSt, respectively. These numbers refer to the standard testing mechanisms used to determine how much resistance to flow (i.e. viscosity) these oils demonstrate.