Blended oils

The importance of following additives

  1. Antioxidants
  2. Corrosion inhibitors
  3. Extreme pressure additives

Petroleum oils are often mixed with chemicals and vegetable or animal oils improve their lubricating property. The chemicals mixed in the lubricating oils are known as additives the type and quantity of additives in blended oils decided after considering the effects of individual additives.

The various additives and their use are given below-



Name of chemical -Phenols, amines, organic sulfides, organic phosphates
Functions – Reduces oxidation of oil formation of sludge

Corrosion inhibitors

Name of chemical -Organ metallic compounds, zinc dithiophosphate, sulfur zed and phosphorised trepans
Functions – Protects metal surface and bearing from corrosion

Extreme pressure additives

Name of chemical -Sulfured fats, chlorinated hydrocarbons, organic phosphorus compounds
Functions– Adsorbs on a metal surface or reacts chemically with metals forming low shear strength layer which prevents tearing up, seizure and welding of metals.


Name of chemical -Fatty acids, fats and fatty amines vegetable oils.
Functions– Increases the strength of oil film and prevents in its rupture

Viscosity improvers

Name of chemical -Polyesters, polystyrenes
Functions– Increase viscosity of the oil

Pour point depressant

Name of chemical -Alkylated naphthalene and phenols, polymethacrylates
Functions-Lowers pour point of lubricants

Antifoaming agents

Name of chemical -Silicone polymers, glycols, glycerol
Functions-Lowers pour point of the lubricant

Viscosity index improvers

Name of chemical -Hexanol, polystyrene, high molecular weight substance
Functions-Reduces rate of change of viscosity with temperature.

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