The NLGI Definition of Incompatibility:

Two lubrication greases show incompatibility when a mixture of the products shows physical properties or service performance which are markedly inferior to those of either the greases before mixing. Peformance or properties inferior to one of the products and superior to the other may be due to simple mixing and wouldn not be concsidered as evidence of incompatibility.

This chart is meant only to serve as a guideline for determining compatibility. For the purposes of changing products in the field, the compatibility of the greases in question should be determined by laboratory testing.