Oil additive
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
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
- 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. Typical detergents are magnesium sulfonates.
- Corrosion or rust inhibiting additives retard the oxidation of metals inside an engine.
- .
- Metal deactivators create a film on metal surfaces to prevent the metal from causing the oil to be oxidized.
- However, organic and inorganic bases and detergents are included in most formulated oils, as discussed in the following paragraph, so some (but not all) of these contaminants will be neutralized. Gear oil degradation and longevity can be measured by its TAN.
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- 's degradation and longevity is its TBN relative to a new oil.
For viscosity
- 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 viscositymodifiers. Some synthetic oils are engineered to meet multi-grade specifications without them. Viscosity modifiers are often plastic polymers. Virtually all oils require a specific range of viscosity as a working fluid, so viscosity is the primary factor that determines if an oil is acceptable for any particular application. As oils degrade from use, their viscosity will decrease, eventually requiring their replacement.
- Pour point depressants improve the oil's ability to flow at lower temperatures.
For lubricity
- Friction modifiers or friction reducers, like molybdenum disulfide, are used for increasing engine fuel economy by reducing friction between moving parts.[6] Friction modifiers alter the lubricity of the base oil. Whale oil was used historically.[7] In [8] it's shown how use of anti-friction additives can increase the power efficiency of a motor.
- Extreme pressure agents bond to metal surfaces, keeping them from touching even at high pressure.
- Zinc dialkyldithiophosphate[9] or zinc dithiophosphatesare typically used.
- Nanoparticles that build diamond-like carbon coatings, which improve embeddability and can achieve superlubricity. The technology is developed with Argonne National Laboratory and Pacific Northwest National Laboratory and the foundation of TriboTEX product.[10] The ability of this technology to reduce and even repair wear was described in NASA Spinoff Magazine.[11]
- Inorganic Fullerene-like Tungsten Disulfide (IF-WS2) .
For contaminant control
- Metal particles released by wear are unintentional and undesirable oil additives. Most large metal particles and impurities are removed in situ using either magnets or oil filters.
- Dispersants keep contaminants (e.g. soot) suspended in the oil to prevent them from coagulating.
- combustion gasescontact metal surfaces.
- Antimisting agents prevent the atomization of the oil. Typical antimisting agents are silicones.[1]
- 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.
For other reasons
- Seal conditioners cause gaskets and seals to swell to reduce oil leakage.
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
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
- Fuel additive
- Gasoline additive
- Oil analysis – Laboratory analysis of an oil based lubricant's properties and contaminants
- Tribology, the science of friction, lubrication and wear
References
- ^
- ^ "API's Engine Oil Guide, 2006" (PDF).
- ^ Chevron Oronite's Diesel Additives
- ^ a b c "TAN & TBN - Spectro Scientific". www.spectrosci.com.
- ^ "Potassium Hydroxide in the Oil and Gas Industry - Continental Chemical".
- ^ Whale oil dexron Turbo hydra-matic 350 By Ron Sessions], page 20.
- ISSN 1729-4061.
- ^ "ZDDP Engine Oil - Mustang Monthly". Mustang 360. Archived from the original on 2009-09-12. Retrieved 2010-06-27.
- ISSN 0301-679X.
- ^ "Nanotechnology Repairs Engine Damage in Cars". NASA Spinoff. 2020.
- ^ 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.
- ^ 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.
- ^ See Nanoflon, a PTFE that is small enough for suspension in lubricants and used commercially for that purpose.
- ^ Presenting PTFE: A Potent Resin, A Well-Kept Secret by Owen Heatwole, April 1981, for QMI.
- ^ "Edwards Engines - Product Specifications". 24 February 2010. Archived from the original on 24 February 2010.
- ^ Quaker State settles FTC charges against Slick 50 for US$10 million in 1997.
- ^ Dura Lube settles FTC charges Archived 2013-01-15 at the Wayback Machine by paying US$2 million in consumer redress in 2000.
External links
- The American Chemistry Council's Petroleum Additives Panel link to oil additive manufacturers.
- How Additives Work Oil Additives link to oil additive manufacturers.