With all of the negative articles about oil additives, which have been written and supported extensively by special interest groups, it’s time to tell the real truth about oil additives. In most cases, they perform a positive function and with regular use can provide a number of benefits to vehicles and equipment.

First, let’s get one thing clear, it’s important to distinguish from oil additives developed by companies that have been extensively tested, and others, usually made by individuals, without the best automatic motor oil such as testing and documentation. Anyone can put an additive package together and have a label made. There are many on the market, which have no real testing, even though, they claim they do. This is where additives have gotten a bad name. On the other hand, there are a number of companies that sell additives that have extensive research and development teams that have tested their additive packages. For example, Lubrizol http://www.lubrizol.com whose revenues were over 4 billion dollars for 2005 specializes in additive packages including aftermarket engines and fuel treatments. Anyone doing this kind of volume is not selling snake oil to millions of dumb consumers—just doesn’t happen. And they are only one of several that are very large. Others include Oronite, Ethyl, Infineum, Bardahl, Wynn’s, SFR, Power Up, STP, Slick 50. This is just a partial list of companies that have well-documented additive products.

In actuality, additives are used in most all lubricants, because even the best synthetic base oils cannot protect vital parts alone, as it’s the additives that do all of the work. Let’s concentrate on the internal combustion engine is looking at the need for additives. According to the American Petroleum Institute the powerful watchdog for the oil companies, “The temperatures and types of service under which an engine is operated vary markedly. Moderate-speed driving on short trips or stop-and-go driving in traffic uses only a fraction of the available engine power. Because the cooling systems must be capable of meeting the cooling requirements of the engine at high speeds, they may overcome the engine in short-trip driving. In such light-duty service engines and motor oils warm up slowly and often do not reach proper operating temperatures.

Under these conditions, automatic chokes will provide the engine with the rich air-fuel mixture it needs to operate smoothly at cold temperatures, but this richness will result in incomplete combustion. Soot and partially oxidized hydrocarbons undergo further oxidation in the crankcase, forming sludge and varnish deposits. These may clog oil screens or plug oil rings, interfering with oil circulation and control, or they may cause hydraulic valve lifters and valves to stick. Corrosive acids are formed that cause wear on piston rings, cylinders, and occasionally on piston skirts. Steam from combustion condenses on cylinder walls and drains into the crankcase. Water, often in combination with acidic gases, may cause valve lifters to rust and stick. It may also create rust deposits on piston pins, rocker arm shafts, and valve stems. Liquid fuel leaking past the piston rings dilutes the oil and reduces its lubricating value. These are some of the effects of engine operation at cold temperatures.

In contrast, legal speed limit driving and long trips allow the engine and oil to warm p properly. The choke is open, and the carburetor is feeding the cylinders with a lean, clean-burning air-fuel mixture. As a result, there is little or no incomplete combustion to produce soot another residue. Under these conditions water compensation is not a problem, nor is the dilution of the motor oil by raw fuel.” Additives have been developed to address these problems as most of us qualify for much of the time for driving in severe service conditions. Furthermore, the API goes on to say “Under some conditions, it is impossible to maintain a continuous oil film between moving parts, and there is intermittent metal-to-metal contact between the high spots on sliding surfaces. Lubrication engineers call this boundary lubrication. Under these circumstances, the load is only partially supported by the oil film. The oil film is ruptured, resulting in significant metal-to-metal contact. When this occurs, the friction generated between the surfaces can produce enough heat to cause one or both of the metals in contact to melt and weld together. Unless counteracted by proper additive treatment, the result is either immediate seizure or the tearing apart and roughening of surfaces.

Boundary lubrication conditions always exist during engine starting and often during the operation of a new or rebuilt engine. Boundary lubrication is also found around the top piston ring where oil supply is limited, temperatures are high, and a reversal of piston motion occurs.

Extreme pressure conditions can develop between heavily loaded parts from lack of lubrication, inadequate clearance, extreme heat, and sometimes as a result of using the wrong type or grade of lubricant for the operating conditions of the engine. Since motor oils do not contain extreme pressure agents this is an area that aftermarket additive manufacturers focus a lot of attention on. In modern engines, the valve train with its cams, valve lifters, pushrods, valve stem tips, and parts of the rocker arms operate under conditions of extreme pressure because they carry heavy loads on very small contact areas. Unit loading, which may be as high as 200,000 pounds per square inch, is many times greater than the loads on the connecting rod bearings or on the piston pins.” Motor oils rarely contain extreme pressure additives, thus premature wear could take place. The preceding has laid the groundwork for the need for additives. Additives to take care of the deposits and sludge, called detergent/dispersant additives, anti-oxidants to delay the effects of oxidation. Anti-foaming additives are important as if foaming occurs in motor oil the film strength is reduced allowing wear. And since base oils alone cannot withstand the metal-to-metal contact inside an engine, anti-wear agents are needed. With acids there is also a need for corrosion inhibitors; and in reducing friction in hydrodynamic lubrication such as on the cylinder liners, where metal-to-metal contact does not occur, friction modifiers or lubricity additives are desired to improve engine efficiency and improve mileage.