The base oils produced of raw oil filtration , or registration of used oil , are not suitable for modem auto mobiles engine and industrial machinery , completely.
so they are added additives to provide suitable traits are as follows 

1. Detergents and dispersants
Dosing fire, a huge amount of smoke and articles due to incomplete firing. Will be appeared these articles are insoluble in oil and produce silt and even may cause to adhesion the ring and the piston. Detergents and dispersants are added to most tribologer oils in order to remove the oil to remove artistes.

And in practice, the materials, the late the oil gets dark, but it cause to sediment the silts and damage to engine, there fare , the oil early getting darkle while working , despite public conception is not indication of its bud quality , at all.

2. viscosity index improver
Viscosity index improver additives molecules of VI improver have long chair polymers and are much large that oil molecules so that spread in oil in cloud form increasing the oil temperature , with solving polymers, the oil viscosity would be compensated . These kinds of oil are used in malt grade oils.

3. arty-oxidant
Same materials in oil due to engine high temperature and continuous content to air and adjacency to engines different metals that might art lithe a catalyst , exposed to continuous oxidation and change to materials like per oxides and organic compounds- to prevent oxidation work condition , engines part including valves and tonsils and,... are rubbed off. anti-wear prevent this . the use of these materials is to provide provide a resistant layer of chemicals between fixed and mobile pouts in order to prevent direct contact with metal and finally wearing .

5. Anti-rust and anti-corrosion
Generally , inorganic oils are capable of protection and prevent rust and corrosion , but in fractions appears. to prevent this. anti rust and anti corrosion are added to most kinds of oils. mean while , basic additives can remove the acids produced due to fire ( in internal combustion engines ) whit cause to rust and corrosion .

6. Pour point depressants.
These materials are added to oil to make possible the combustion of the engine and set it in motion in too cold temperature, with help of these materials , the paraffin articles are kept suspension at law temperature in oil and are prevented farm getting solid

7. Anti-foam
While engine and industrial machines working , due to hitch speed of movement and call-in soon. the entering air into oil cause foam. to prevent this situation and damage possibility, anti-foam are added.