Oil additive

  1. Oil additives
  2. Corrosion inhibitors


An oil additive is used to improve the base oil (or oil "base stock") into a better performing lubricant. By utilizing the same base stock, many different oils can be manufactured, each with its own unique properties.

Nearly all motor oils currently being sold have an additive package, whether they are synthetic or petroleum based. Essentially, only the American Petroleum Institute (API) Service SA motor oils have no additives whatsoever, and they are therefore incapable of protecting modern engines.[1] Different additives are used depending on 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).

According to a source in the petroleum industry,

"A lubricant additive package can comprise anywhere from 1% of a finished hydraulic oil to approximately 20% of a typical multi-grade motor oil."[2]

Types of additives

  • Detergent additives, dating back to the early 1930s,[3] are used to clean and neutralize oil impurities which would normally cause deposits (oil sludge) on vital engine parts.
  • Friction modifiers, like molybdenum disulfide,[4] are used for increasing fuel economy by reducing friction between moving parts. Friction modifiers alter the lubricity of the base oil. Whale oil was used historically.[5]
  • Viscosity modifiers make an oil's viscosity higher at elevated temperatures, improving its viscosity index (VI). This combats the tendency of the oil to become thin at high temperature. The advantage of using less viscous oil with a VI improver is that it will have improved low temperature fluidity as well as being viscous enough to lubricate at operating temperature. Most multi-grade oils have viscosity modifiers. Some synthetic oils are engineered to meet multi-grade specifications without them.
  • Corrosion or rust inhibiting additives retard the oxidation of metal inside an engine.
  • Antioxidant additives retard the decomposition of the stock oil.
  • Antiwear additives or wear inhibiting additives cause a film to surround metal parts, helping to keep them separated. Zinc dialkyldithiophosphate (ZDDP) is a popular antiwear additive and has showed lower wear number in flat tappet style engines (like the 4.0 from jeep), the use of which has been restricted due to potential damage to catalytic converters forced upon automakers by government regulation.[6]
  • Pour point depressants improve the oil's ability to flow at lower temperatures.
  • Anti-foam agents inhibit the production of air bubbles and foam in the oil which can cause a loss of lubrication, pitting, and corrosion where entrained air contacts metal surfaces.
  • Seal conditioners cause gaskets and seals to swell so that the oil cannot leak by.
  • Metal deactivators create a film on metal surfaces to prevent the metal from causing the oil to be oxidized.
  • Extreme pressure agents bond to metal surfaces, keeping them from touching even at high pressure.
  • Dispersants keep contaminants (e.g. soot) suspended in the oil to prevent them from coagulating.
  • Wax crystal modifiers are dewaxing aids that improve the ability of oil filters to separate wax from oil. This type of additive has applications in the refining and transport of oil, but not for lubricant formulation.
  • Wear metals from friction are unintentional oil additives, but most large metal particles and impurities are removed in situ using either magnets or oil filters made for this purpose. See tribology, the science that studies how materials wear.

Additives in the aftermarket and controversy

Although motor oil is manufactured with numerous additives, aftermarket oil additives exist, too. 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.

Some mass-market oil additives, notably the ones containing PTFE/Teflon (e.g. Slick 50)[7] and chlorinated paraffins (e.g. Dura Lube),[8] have caused a major backlash by consumers and the U.S. Federal Trade Commission which 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.

Although PTFE, a solid, was used in some aftermarket oil additives, users alleged that the PTFE clumped together, clogging filters. Certain people in the 1990s have reported that this was corroborated by NASA[9] and U.S. universities.[10] One thing to note, in defense of PTFE, is that if the particles are smaller than what was apparently used in the 1980s and 1990s, then PTFE can be an effective lubricant in suspension.[11] 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",[12][13] it would hardly do any good if it remains in the oil filter.

The US Department of Defense (DoD) restricts the use of aftermarket fuel and oil additives.[14]

See also

External links

References

  1. ↑ API's Engine Oil Guide, 2006
  2. ↑ from Afton Chemical website
  3. ↑ Chevron Oronite's Diesel Additives
  4. ↑ Inventor Jonathan McConnachie of ExxonMobil Research and Engineering (EMRE) developed molybdenum sulfide as an oil additive
  5. ↑ Whale oil dexron Turbo hydra-matic 350 By Ron Sessions], page 20.
  6. ↑ http://www.mustangmonthly.com/techarticles/mump_0907_zddp_zinc_additive_engine_oil/index.html
  7. ↑ Quaker State settles FTC charges against Slick 50 for US$10 million in 1997.
  8. ↑ Dura Lube settles FTC charges by paying US$2 million in consumer redress in 2000.
  9. ↑ 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.
  10. ↑ 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.
  11. ↑ See Nanoflon, a PTFE that is small enough for suspension in lubricants and used commercially for that purpose.
  12. ↑ Presenting PTFE: A Potent Resin, A Well-Kept Secret by Owen Heatwole, April 1981, for QMI.
  13. ↑ QMI Products ad
  14. ↑ DoD Policy Guidance For Use of Aftermarket Fuel & Lubricant Additives - July 1996
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