Lubricants are manufactured to meet particular qualities that include high boiling points, low freezing points, high viscosity indices, thermal stability, hydraulic stability, corrosion resistance, and resistance to oxidation, even at elevated temperatures.
Petroleum lubricants are manufactured from base oils that are isolated from high boiling fractions of crude oil that are often referred to as mineral oils. Base oils are produced through sequential processing of crude oil that includes basic:
- distillation, to isolate the fraction of crude oil suitable for the mineral oil’s intended end use
- deasphalting, to remove undesirable heavy fractions of oil that can lead to gumming and other undesirable characteristics extraction or solvent refining, to reduce or remove aromatics and related heteroatomic compounds
- dewaxing, to remove undesirable paraffins and other alkanes that can otherwise crystallize in the oil at low temperatures
- hydrotreating, to remove olefins and other unstable compounds from the base oil that can lead to smoking at high temperatures, an/or overall product instability
Blends of naphthenic and paraffinic base oils are used to control viscosity of different lube oils as, generally, paraffinic base oils have higher viscosities and resist oxidation better than naphthenic base oils, making paraffinic-rich lube oils better suited for higher-temperature applications.
Marketable lubricants are produced from blends of various base oil stocks and additives (e.g., emulsifiers, surfactants, corrosion inhibitors, etc.).
Blends of base oils with additives are formulated to achieve desired viscosity, thermal stability, foaming characteristics, seal compatibility, compressibility, oxidation resistance, corrosivity, cloud point, pour point, and high-temperature properties such as volatility and flash point.