Grease miscibility

Mixing lubricants, whatever their consistency and whatever their composition, is a practice that is discouraged from the point of view of good lubrication practice. The reason is that the properties of the mixture of various lubricants may be altered and the actual behavior of said mixture, in practice, may differ from the theoretically expected.

However, on many occasions it is very difficult to avoid mixing lubricants, especially mixing greases, for technical or economic reasons, for which it is necessary to have a basic miscibility guide that allows us to program the best lubricant change operation every time.

For this, the miscibility of its main components is taken into account, that is, between base oils and between thickeners, which is summarized in the following tables.

Base Oil Miscibility

+: miscible,  -:non miscible,  +/-: depends on base oil type

Thickener Miscibility

+: miscible,  -: non miscible,  *:consult your FUCHS specialist

To determine whether two specific lubricating greases are fully miscible, laboratory tests must be carried out with different degrees of mixing (proportions, for example, 20/80, 50/50, 80/20).

The miscibility tests do not serve to guarantee that the performance of the mixture of both greases is the same as that of the separate products, for which the study has to be completed with mechanical-dynamic tests with different degrees of mixing. However, they make it possible to predict effects such as inhomogeneous mixing of fats, a clear separation of the mixture into two phases, a loss of consistency of the mixture, an extreme variation in the dropping point or an oil separation and to foresee the most appropriate measures. suitable for programming a correct transition between lubricants.