The film thickness–roughness ratio Λ has been used since the mid-1960s as a criterion for the lubrication conditions in rolling bearings. However, due to an assumed Gaussian distribution of the roughness height amplitudes of the functional surfaces of rolling bearings and other unsubstantiated assumptions concerning the mechanisms of contact interaction, concerns have arisen about the representability of Λ in terms of lubrication. In this study, a more objective Λ-type ratio that does not depend on the law of roughness height distribution and the peculiarities of contact mechanics is introduced and defined as Λz. The relevant range of the new Λ ratio, which identifies a full-film lubrication, is lower than that of its conventional counterpart, and it coincides directionally with contemporary theoretical and experimental results. The study exhibits unique profilometric data of the functional surfaces of the roller bearings, produced by the major bearing manufacturers. Based on the extensive and precision inspection of the surface texture of a representative quantity of these bearings, a substantial deviation of their functional surfaces from normality has been demonstrated.