Base Oil

Base oil is the primary ingredient in the formulation of lubricants, accounting for approximately 70-90% of the final product, depending on its application. It plays a crucial role in determining the performance characteristics, stability, and longevity of lubricating oils used in a variety of mechanical systems. Base oils are derived either from refining crude petroleum or through chemical synthesis, and they form the foundation upon which additives are blended to enhance functionality.

There are five main groups of base oils categorised by the American Petroleum Institute (API). Groups I, II, and III are mineral-based, extracted from petroleum using different refining processes. Group I oils are solvent-refined and contain more impurities, making them suitable for less demanding applications. Group II oils undergo hydrocracking, which removes more unwanted components, resulting in better oxidation stability and performance. Group III base oils are the most refined of the mineral oils, often qualifying as synthetic due to their high viscosity index and purity.

Group IV base oils consist of polyalphaolefins (PAO), a type of synthetic oil that offers excellent thermal and oxidative stability. They perform exceptionally well in extreme temperature conditions and are commonly used in high-performance automotive and industrial lubricants. Group V includes all other base oils that don’t fit into the first four groups, such as esters, polyalkylene glycols (PAG), and silicones. These are often used for specialised applications, including environmentally friendly lubricants, refrigeration systems, or aviation.

The properties of base oil significantly impact the final lubricant’s viscosity, volatility, oxidative stability, and performance at high and low temperatures.