Oil additives are chemical compounds that improve the lubricant performance of base oil (or oil "base stock"). The manufacturer of many different oils can utilize the same base stock for each formulation and can choose different additives for each specific application. Additives comprise up to 5% by weight of some oils.[1]

Nearly all commercial motor oils contain additives, whether the oils are synthetic or petroleum based. Essentially, only the American Petroleum Institute (API) Service SA motor oils have no additives, and they are therefore incapable of protecting modern engines.[2] The choice of additives is determined by the application, e.g. the oil for a diesel engine with direct injection in a pickup truck (API Service CJ-4) has different additives than the oil used in a small gasoline-powered outboard motor on a boat (2-cycle engine oil).

Types of additives

Oil additives are vital for the proper lubrication and prolonged use of motor oil in modern internal combustion engines. Without many of these, the oil would become contaminated, break down, leak out, or not properly protect engine parts at all operating temperatures. Just as important are additives for oils used inside gearboxes, automatic transmissions, and bearings. Some of the most important additives include those used for viscosity and lubricity, contaminant control, for the control of chemical breakdown, and for seal conditioning. Some additives permit lubricants to perform better under severe conditions, such as extreme pressures and temperatures and high levels of contamination.

Controlling chemical breakdown

Chemical structure of a zinc dialkyldithiophosphate, a typical antiwear agent found in many motor oils.

For viscosity

For lubricity

Nanoparticle flakes from the oil additive TriboTEX. Image taken with electron microscope showing the nano scale.
TEM image of a group of scientific-grade nanoparticles manufactured by Nanotech Industrial Solutions. Note the near-spherical shape and presence of a hollow core.

For contaminant control

For other reasons

Additives in the aftermarket and controversy

Motor oil is manufactured with numerous additives, and there are also aftermarket additives. A glaring inconsistency of mass-marketed aftermarket oil additives is that they often use additives which are foreign to motor oil. On the other hand, commercial additives are also sold that are designed for extended drain intervals (to replace depleted additives in used oil) or for formulating oils in situ (to make a custom motor oil from base stock). Commercial additives are identical to the additives found in off-the-shelf motor oil, while mass-marketed additives have some of each.

Although PTFE, a solid, was used in some aftermarket oil additives, some users said that the PTFE clumped together, clogging filters. Certain people in the 1990s reported that this was corroborated by NASA[12] and U.S. universities.[13] However, if the PTFE particles are smaller than those apparently used in the 1980s and 1990s, then PTFE can be an effective lubricant in suspension.[14] The size of the particle and many other interrelated components of a lubricant make it difficult to make blanket statements about whether PTFE is useful or harmful. Although PTFE has been called "the slickest substance known to man",[15][16] it would hardly do any good if it remains in the oil filter.

Some mass-market engine oil additives, notably the ones containing PTFE/Teflon (e.g. Slick 50)[17] and chlorinated paraffins (e.g. Dura Lube),[18] caused a major backlash by consumers; the U.S. Federal Trade Commission investigated many mass-marketed engine oil additives in the late 1990s. Although there is no reason to say that all oil additives used in packaged engine oil are good and all aftermarket oil additives are bad, there has been a tendency in the aftermarket industry to make unfounded claims regarding the efficacy of their oil additives. These unsubstantiated claims have caused consumers to be lured into adding a bottle of chemicals to their engines which do not lower emissions, improve wear resistance, lower temperatures, improve efficiency, or extend engine life more than the (much cheaper) oil would have. Many consumers are convinced that aftermarket oil additives work, but many consumers are convinced that they do not work and are in fact detrimental to the engine. The topic is hotly debated on the Internet.

See also


  1. ^ a b Thorsten Bartels et al. "Lubricants and Lubrication" in Ullmann's Encyclopedia of Industrial Chemistry, 2005, Weinheim. doi:10.1002/14356007.a15_423
  2. ^ "API's Engine Oil Guide, 2006" (PDF).
  3. ^ Chevron Oronite's Diesel Additives
  4. ^ a b c "TAN & TBN - Spectro Scientific". www.spectrosci.com.
  5. ^ "Potassium Hydroxide in the Oil and Gas Industry - Continental Chemical".
  6. ^ Roger F. Sebenik et al. "Molybdenum and Molybdenum Compounds" in Ullmann's Encyclopedia of Chemical Technology 2005; Wiley-VCH, Weinheim. doi:10.1002/14356007.a16_655
  7. ^ Whale oil dexron Turbo hydra-matic 350 By Ron Sessions], page 20.
  8. ^ Mytrofanov, Oleksandr; Proskurin, Arkadii; Poznanskyi, Andrii; Zivenko, Oleksii (2023-08-31). "Determining the effect of anti-friction additive on the power of mechanical losses in a rotary piston engine". Eastern-European Journal of Enterprise Technologies. 4 (1 (124)): 28–34. doi:10.15587/1729-4061.2023.284500. ISSN 1729-4061.
  9. ^ "ZDDP Engine Oil - Mustang Monthly". Mustang 360. Archived from the original on 2009-09-12. Retrieved 2010-06-27.
  10. ^ Chang, Qiuying; Rudenko, Pavlo; Miller, Dean J.; Wen, Jianguo; Berman, Diana; Zhang, Yuepeng; Arey, Bruce; Zhu, Zihua; Erdemir, Ali (2017). "Operando formation of an ultra-low friction boundary film from synthetic magnesium silicon hydroxide additive". Tribology International. 110: 35–40. doi:10.1016/j.triboint.2017.02.003. ISSN 0301-679X.
  11. ^ "Nanotechnology Repairs Engine Damage in Cars". NASA Spinoff. 2020.
  12. ^ A NASA research report is purported to say about PTFE oil additives, "In the types of bearing surface contact we have looked at, we have seen no benefit. In some cases we have seen detrimental effect. The solids in the oil tend to accumulate at inlets and act as a dam, which simply blocks the oil from entering. Instead of helping, it is actually depriving parts of lubricant." The source of this quote is unknown, but the quote itself appears in the magazine article referenced below.
  13. ^ See Road Rider Magazine (now Motorcycle Consumer News) article from August 1992 by Fred Rau, which has been reprinted extensively, and see oilsfilters.htm for a contemporary discussion.
  14. ^ See Nanoflon, a PTFE that is small enough for suspension in lubricants and used commercially for that purpose.
  15. ^ Presenting PTFE: A Potent Resin, A Well-Kept Secret by Owen Heatwole, April 1981, for QMI.
  16. ^ "Edwards Engines - Product Specifications". 24 February 2010. Archived from the original on 24 February 2010.
  17. ^ Quaker State settles FTC charges against Slick 50 for US$10 million in 1997.
  18. ^ Dura Lube settles FTC charges Archived 2013-01-15 at the Wayback Machine by paying US$2 million in consumer redress in 2000.