What are Base oils?
A word base oil in lubricants industry is typically used for oils thoes are extracted from a crude oil via fractional distillation process. There are different types of base oil such as:
Minearal Base Oils
Mineral oils, derived from refining heavy crude oil, are a primary base for lubricants. Comprising paraffinic, naphthenic, and aromatic oils, they offer varying degrees of stability and solubility. While paraffinic oils exhibit chemical stability suitable for lubricants, naphthenic and aromatic oils are less stable and prone to oxidation, leading to reduced usage in modern products.
Synthetic Base Oils
The word SYNTHETIC literally means a substance made by chemical synthesis, especially to imitate a natural product. In general no base oils are existing in our environment, they all are extracted from crude oil or natural resources by processing them on a commercial levels such as distillation of crude in refineries. Synthetic Lubricants or synthetic oils are refined from the crude oil, to learn and understand this we have to learn few things about base oils, the word ‘synthesized’ is literally correct for the lubricants as they are synthesized during the process of distillation of crude oil, this synthesized process is called Hydrocracking.
Synthetic oil, composed of artificially modified chemical compounds, is a versatile lubricant. While it’s commonly derived from chemically altered petroleum components, alternative raw materials can also be used in its synthesis. Although distilled crude oil serves as the primary base, the synthesis process and additive composition differ among manufacturers, remaining proprietary. Synthetic oils are highly effective in extreme temperature conditions, making them ideal for applications such as aircraft jet engines and metal stamping, where environmental benefits are paramount.
Base oils are can be further catogarised into following groups:
- Group I or group 1 base oils
- Group II or group 2 base oils
- Group III or group 3 base oils
- Group IV or group 4 base oil or PAO(Polyalphaolefin)
- Group V or Group 5 base oils
Group 1 Base Oils
Group I base oils are classified as less than 90 percent saturates, greater than 0.03 percent sulfur and with a viscosity-index range of 80 to 120. The temperature range for these oils is from 32 to 150 degrees F. Group I base oils are solvent-refined, which is a simpler refining process. This is why they are the cheapest base oils on the market.
Group 2 Base Oils
Group II base oils are defined as being more than 90 percent saturates, less than 0.03 percent sulfur and with a viscosity index of 80 to 120. They are often manufactured by hydrocracking, which is a more complex process than what is used for Group I base oils. Since all the hydrocarbon molecules of these oils are saturated,
Group II base oils have better antioxidation properties. They also have a clearer color and cost more in comparison to Group I base oils. Still, Group II base oils are becoming very common on the market today and are priced very close to Group I oils.
Group 3 Base Oils
Group III base oils are greater than 90 percent saturates, less than 0.03 percent sulfur and have a viscosity index above 120. These oils are refined even more than Group II base oils and generally are severely hydrocracked (higher pressure and heat). This longer process is designed to achieve a purer base oil.
Group III base oils are sometimes described as synthesized hydrocarbons or synthetic. Like Group II base oils, these oils are also becoming more prevalent.
Group 4 Base Oils
Group IV base oils are polyalphaolefins (PAOs). These synthetic base oils are made through a process called synthesizing. They have a much broader temperature range and are great for use in extreme cold conditions and high heat applications.
Group 5 Base Oils
Group V base oils are classified as all other base oils, including silicone, phosphate ester, polyalkylene glycol (PAG), polyolester, biolubes, etc. These base oils are at times mixed with other base stocks to enhance the oil’s properties. An example would be a PAO-based compressor oil that is mixed with a polyolester.
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.