Antiwear additives

AW additives, or antiwear additives, are additives for lubricants to prevent metal-to-metal contact between parts of gears.

EP additives are used in applications such as gearboxes, while AW additives are used with lighter loads such as bushings.

Some popular AW additives are:

Some formulations use colloidal PTFE (Teflon), but its efficiency is controversial.

Many AW additives function as EP additives, for example organophosphates or sulfur compounds. The mechanism of function of TCP and ZDDP is explained in EP additives.

Under extreme pressure conditions, the performance of AW additives becomes insufficient and designated EP additives are required.

...
Wikipedia