They are obtained by esterification of a monoalcohol and a diacid. These unctuous oils have a very high solvent power, a high anti-wear power, a very low pour point

These unctuous oils have a very high solvent power, a high anti-wear power, a very low pour point which can reach -73°C, and form very few residues at high and very high temperatures. On the other hand, they are aggressive towards paints and some elastomer qualities and are sensitive to hydrolysis, so they are not very suitable for working in the presence of moisture.

 

They are frequently used in combination with PAO oils, particularly to balance their action on joints or to promote the solubility of certain additives.