At a meeting of the Auto-Oil Advisory Panel (AOAP) in Denver, Colorado, U.S.A., on Thursday, a representative from General Motors (GM) expressed concern when a fully formulated oil originally blended with “Group III+” base oil showed a drop in performance when the formulation was switched to a Group III base oil. This was apparently detected in an aftermarket audit of dexos licensees conducted by the U.S. automaker.
“We have seen a pattern that products that are approved with “Group III+” showed lower performance when replaced with a non-plus,” the specification-development body for the API S Service Category was told.
Although no formal request was made to the group, GM’s concern was referred to the API Base Oil Interchange (BOI)/Viscosity Grade Read Across (VGRA) Task Force, who in turn asked the OEM for additional data, especially the base oil formulation.
“We have seen a pattern that products that are approved with “Group III+” showed lower performance when replaced with a non-plus,” the specification-development body for the API S Service Category was told.
Although no formal request was made to the group, GM’s concern was referred to the API Base Oil Interchange (BOI)/Viscosity Grade Read Across (VGRA) Task Force, who in turn asked the OEM for additional data, especially the base oil formulation.
... Fine time. 
