Engine Oil Additives - This Is A Subject Of Some Controversy
Engine Oil Additives – This Is A Subject Of Some Controversy

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So, Engine oil additives are chemical compounds; that improve the lubricant performance of a base oil. Actually, nearly all oils contain additives (from 10 to 30%), whether the oils are synthetic or petroleum based.

Engine oil additives have three basic roles:

  1. Enhance existing base oil properties with antioxidants, corrosion inhibitors, antifoaming agents and emulsifying agents.
  2. Suppress undesirable base oil properties with pour-point depressants and viscosity index (VI) improvers.
  3. Impart new properties to base oils with extreme pressure (EP) additives, detergents, metal deactivators and tackiness agents.

The most important engine oil additives:

So, The best engine oil additives are, oil stabilizers and viscosity modifiers. Because, they help the oil last longer and in a sense they are “restore engine additives”. You’ve probably heard of extreme wear additives as being; the best engine oil additives. That’s because, they improve or extend the oil’s extreme pressure protection capacity.

So, the bottom line is, engine oil additives, reduce engine wear and increase fuel efficiency.

Above all, viscosity is the most important property of a base oil. However, there is more to lubricants than just viscosity. Thats why, It’s crucial to understand the role of additives; and their function(s) within the lubricant. Oil additives typically range between 0.1 to 30 percent of the oil volume.

Other Important Information About additives:

More additive is not always better. The old saying, “If a little bit of something is good, then more of the same is better”. But, This is not necessarily true when using oil additives. So, Increasing the percentage of a certain additive may improve one property of an oil. While, at the same time degrade another. When the specified concentrations of additives become unbalanced; overall oil quality can be affected.

Some additives compete with each other for the same space on a metal surface.

Consequently, For many additives, the longer the oil remains in service; the less effective the remaining additive package is. When the additive package weakens, viscosity increases, sludge begins to form; corrosive acids start to attack bearings and metal surfaces. Finally, It is for these reasons that top-quality lubricants; meeting the correct industry specifications should always be selected.

Basic Functions Of Additives:

Anti-Wear Agents

  • Reduce friction and wear, and prevent scoring and seizure.

Corrosion & Rust Inhibitors

  • Prevent corrosion and rusting of metal parts in contact with the lubricant.


  • Keep surfaces free of deposits and neutralize corrosive acids.


  • Keep insoluble soot dispersed in the lubricant.

Friction Modifiers

  • Alter coefficient of friction.

Viscosity Improvers

  • Reduce the rate of viscosity change with temperature.

Anti-Foaming Agents

  • Prevent lubricant from forming a persistent foam.


  • Retard oxidative decomposition.

Metal Deactivator

  • Reduce catalytic effect of metals on oxidation rate.

So, It is evident from the information above, that there is a lot of chemistry occurring in most engine oils. It is for those reasons that the mixing of different oils; and adding additional lubricant additives should be avoided.

Aftermarket Additives

So, There are hundreds of chemical additives and supplemental lubricant conditioners available. And, In certain specialized applications or industries; these additives may have a place in the improvement of lubrication.

However, some manufacturers will make claims about their products that are exaggerated. As a result, they fail to mention a negative side effect that the additive may cause.

Take great care in the selection and application of these products, or better still, avoid using them. If you want a better oil, buy a better oil in the first place; and leave the chemistry to the people who know what they are doing.

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