Saphonification Value:

It can be defined as the number of milligrams of KOH required to saponify one gram of oil. It is nothing but Alkaline Hydrolysis of pure oil giving soap & glycerol.

Significance:

It helps us to know the stability of the oil in aqueous/alkaline medium if in case machine parts face any such conditions. It also signifies the composition of vegetable/animal oils, thereby helps to check the suitability of oils for lubrication purpose. Drying property of oils which is harmful during lubrication can also be checked.