Paraffins are desirable in lubricating oil, as it has got high

B viscosity index
The Viscosity Index (VI) is a measure of how much a lubricant's viscosity changes with temperature. It's essentially a way to assess how stable a lubricant's viscosity remains over a range of temperatures. A high VI indicates that the lubricant's viscosity doesn't change much with temperature, while a low VI means the viscosity changes significantly
It means why paraffins used good at lubrication and grease as it has waxy and viscous texture
Smoke point is used to indicat aromatic if it high that mean less aromatic compound and then no black smoke emission