Viscosity Index Improver additif ialah polimer molekulmakro yang dicipta untuk mempengaruhi perubahan kelikatan minyak enjin bergantung kepada suhu.
Polimer ini mengecut apabila pada suhu rendah & seterusnya menyamakan perubahan kelikatan minyak enjin pada suhu rendah
Viscosity index improvers are macromolecular polymers (combination of macromolecules) that are constructed in such a way that they influence the temperature-dependent viscosity change of an oil. The polymer contracts at low temperatures. This makes the resistance that the polymer opposes an invading body with smaller and the viscosity change of the base oil is equalized