AW additives, orantiwear additives, areadditives forlubricants to prevent metal-to-metal contact between parts ofgears.^[1]

EP additives are used in applications such asgearboxes, while AW additives are used with lighter loads such asbushings.

Some popular AW additives are:

• zinc dithiophosphate (ZDP)
• zinc dialkyl dithio phosphate (ZDDP), probably the most widely used^[2] in formulatedengine oils, also acts as acorrosion inhibitor andantioxidant
• Tricresyl phosphate (TCP), used for high-temperature operation, often used as an AW and EP additive in turbine engine lubricants, and also in some crankcase oils andhydraulic fluids
• Halocarbons (chlorinated paraffins), for extreme pressure operations
• Glycerol mono oleate
• Stearic acid, adhering to surfaces via reversible adsorption process under 150 °C, which limits its use to mild contact conditions.

Some formulations usecolloidalPTFE (Teflon), but its efficiency is controversial.

Many AW additives function as EP additives, for exampleorganophosphates orsulfur compounds. The mechanism of function of TCP and ZDDP is explained inEP additives.

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

• Extreme pressure additive
• Oil additive – Chemical compounds that improve the lubricant performance of base oil

• Lubricants
• Oil additives

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• Short description matches Wikidata