Which factor is NOT considered in film lubrication effectiveness?

Film lubrication effectiveness is primarily influenced by factors that directly relate to the ability of the lubricant to form a sufficient protective layer between moving parts. Viscosity is crucial because it determines how well the lubricant can maintain a film under varying temperatures and pressures. Running clearances affect how much lubricant can be retained in the gap between the moving surfaces, which is vital for adequate lubrication. The condition of bearing surfaces plays a significant role because surface roughness and wear can significantly impact how effectively the lubricant can do its job.

Time of day, however, is irrelevant to lubrication effectiveness. It does not impact the physical properties of the lubricant, the mechanical behavior of the components, or the environmental conditions affecting the lubrication system. Thus, it is not a factor that would be considered when evaluating the effectiveness of film lubrication.