In order to help keep the engines clean many oil manufacturers often include other additives in addition to the viscosity index improvers. This minimizes sludge build-up, corrosion inhibitors, and alk...
In order to help keep the engines clean many oil manufacturers often include other additives in addition to the viscosity index improvers. This minimizes sludge build-up, corrosion inhibitors, and alkaline additives to neutralize acidic oxidation products of the oil. The following are other additives available commercially which can be added to the oil by the user for additional benefit. These include:
• Zinc dialkyldithiophosphate (ZDDP) additives, which typically also contain calcium, are available to consumers for additional protection under extreme-pressure conditions or in heavy duty performance situations. ZDDP and calcium additives are also added to protect motor oil from oxidative breakdown and to prevent the formation of sludge and varnish deposits.
• In the 1980s and 1990s, additives with suspended PTFE particles were available to consumers to increase motor oil’s ability to coat and protect metal surfaces. There is controversy as to the actual effectiveness of these products as they can solidify and clog oil filters.
• Some molybdenum disulfide containing additives to lubricate oils are claimed to reduce friction, bond to metal, or have anti-wear properties.
Most commercial oils have a minimal amount of ZDDPs as an anti-wear additive to protect contacting metal surfaces with zinc and other compounds in case of metal to metal contact. The quantity of ZDDP is limited to minimize adverse effect on catalytic converters.