Additives in oil - meaning and tasks

Additives are added to a product in order to impart certain properties to it or to weaken undesirable properties. They change the properties of lubricants through chemical and physical effects. Additives play an important role at ADDINOL. Already in the company name (abbreviation for "Additives in Oil") it is pointed out that additives are an elementary component of our lubricants. The base oils that we use for our production do not meet all the requirements placed on a lubricant in use. For example, wide temperature ranges and load peaks in engines for oils can only be handled if the appropriate additives are added. With some oils, additive proportions of up to 30% are achieved.

Additives in general have the following tasks:

  • Additives maintain your engine, gearbox or industrial plant from the inside.
  • Additives actively protect against wear and corrosion.
  • Their effectiveness increases the performance and service life of the engine, gearbox or industrial plant.

We then compiled the most important additives required for engine oils, gear oils and industrial lubricants.

AdditivesCharacteristicsActive ingredients
Anti-foam additives
  • Prevention of foam formation in oil and acceleration of foam decomposition
  • Reducing the tendency to foam during strong movement and air entry
  • Polysiloxanes
  • Polyalkylene glycol ether
  • Improvement of the water separating capacity of a lubricant
  • Prevention of water-oil emulsions
  • Anion-active compounds such as alkali or alkaline earth salts
  • Dispersants: Keeps the smallest foreign matter (soot, coke etc.) in the oil in suspension and transports it to the filter
  • Detegergents: Prevention of sludge formation by dissolving deposits, neutralization of acids
  • Detergents: sulfonates, phenates, phosphates, calcium and magnesium salts
  • Dispersants: succinic acid compounds such as succinimides and esters
  • Reducing the surface tension of water
  • Formation of a stable emulsion of oil and water
  • Fatty acids
  • Fatty soaps
  • Ammonium salts
  • Polyglycols
EP additives (extreme pressure)
  • Anti-fouling additives with high pressure resistance
  • Keep lubricant film stable even at high pressure
  • Prevent seizure and welding of the friction partners
  • Sulphur compounds
  • Phosphorus compounds
  • Chlorinated paraffins
  • Molybdenum compounds
  • Improvement of adhesion properties to surfaces
  • Especially important for lubricating greases and chain oils
  • High molecular weight hydrocarbons such as polyisobutylene
Corrosion inhibitors
  • Protection of metallic surfaces against moisture through the formation of a water-repellent barrier
  • Avoidance of rust by neutralization of acids
  • Salts of carboxylic and dicarboxylic acids
  • Sulfonates
  • Waxes
Oxidation inhibitors (Antioxidants)
  • Slow down the reaction of lubricating oils with oxygen
  • Slow down oil aging
  • Delay oil thickening, acidification, sludge formation etc.
  • Amines
  • Phenols
  • Phosphites
  • Sulphites
Pourpoint depressant (PPD)
  • Improvement of the flowability of a lubricant at low temperatures
  • Thickening of the oil due to the paraffin crystals growing together is prevented
  • Paraffin-alkylated naphthalenes and phenols
  • Polymethacrylates
Friction modifier
  • Setting the appropriate friction coefficient characteristic for lubricants
  • In most cases, the reduction of friction is the goal
  • Fatty acids
  • Amines
  • Amine phosphates
  • Mild EP additives
Anti-wear additives
  • Adhesion to metal surfaces due to polarity
  • AW additives prevent contact between the friction partners in the mixed friction area
  • Prevent seizure and wear
  • Phosphorus and sulphur compounds
  • Zinc dithiophosphates
  • Olefins
  • Fatty acid esters
  • Molybdenum disulphide
  • Graphite
VI improver
  • Optimise viscosity-temperature behaviour of lubricants
  • Lubricant remains flowable at low temperatures and does not thicken too much
  • When heated, the lubricant does not become too thin so that the lubricating film does not break off
  • Olefin copolymers
  • Polymethacrylates
  • Styrene-butadiene copolymers

Additives are particularly important for engine oils. Depending on the manufacturer, engine concept and design, special additive mixtures are required that have to be specifically adapted. This results in many manufacturer specifications, which in turn entail a large number of special oils.

Additives were added to oil in the laboratory
The correct ratio of additives in the oil must be precisely adjusted

Should additives be added separately to the lubricant?

No, because additives can only work properly if they are added to the base oil in the correct proportion. The perfect combination is determined with lengthy tests in the laboratory. Therefore, do not mix any special additives into lubricants that have already been composed. Automotive manufacturers in particular advise against adding additives separately. It can happen that the lubricant then no longer works as desired and long-term damage occurs to the friction partners. The oils of ADDINOL meet numerous manufacturer specifications and can therefore be used in the original mixing ratio.

The only recommendation we give you with regard to additionally filled additives is to use an engine flush before an oil change in order to remove as many dirt particles as possible with the used oil.

Additives for other applications

Additives are not only used in lubricants. The addition of additives also makes sense in other products. In many products the admixture of additives is even prescribed. Fuels such as diesel or gasoline therefore meet the requirements of modern engines. This increases the knock resistance of petrol or makes diesel more resistant to cold temperatures.

Typical products to which additives are added:

  • Fuels such as diesel, petrol or heating oil
  • Coating materials such as lacquers
  • Synthetic materials
  • Food industry (changes in consistency, taste, colour, shelf life, etc.)

Additives occur in the everyday life of every human being, to a certain extent, even though not everyone is aware of it.


Heiko Stephan

Application Technology

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