Almost every lubricant used in plants today started off as just a base oil. The American Petroleum Institute (API) has categorized base oils into five categories, mentioned below. The first three groups are refined from petroleum crude oil. Group IV base oils are full synthetic (polyalphaolefin) oils. Group V is for all other base oils not included in Groups I through IV. Before all the additives are added to the mixture, lubricating oils begin as one or more of these five API groups. All lubricants contain a base oil. It serves as the foundation of the lubricant before it is blended with additives or a thickener in the case of grease.
All base oils have characteristics that determine how they will hold up against a variety of lubrication challenges. For a mineral oil, the goal of the refining process is to optimize the resulting properties to produce a superior lubricant. For synthetically generated oils, the objective of the various formulations is to create a lubricant with properties that may not be achievable in a mineral oil. Whether mineral-based or synthetic-based, each base oil is designed to have a specific application.
Some of the most important base oil properties include the viscosity limitations and viscosity index, pour point, volatility, oxidation and thermal stability, aniline point (a measure of the base oil’s solvency toward other materials including additives), and hydrolytic stability (the lubricant’s resistance to chemical decomposition in the presence of water).
Present-day Group II base oils are the most commonly used base oils in plants. Currently, Group III accounts for less than 1 percent of the capacity in plants. Group I base oils previously made up 56 percent of the capacity, compared to 28 percent of the capacity in today’s plants.
The American Petroleum Institute (API), categorized base oils into five main groups. This breakdown is based on the refining method and the base oil’s properties in terms of, among other things, viscosity and the proportion of saturates and sulfur content.
Group V
These base oils are at times mixed with other base stocks to enhance the oil’s properties. Esters are common Group V base oils used in different lubricant formulations to improve the properties of the existing base oil. Ester oils can take more abuse at higher temperatures and will provide superior detergency compared to a PAO synthetic base oil, which in turn increases the hours of use.