Base Oil
Category |
Manufacturing
Method |
Oil Characteristics |
| Group I |
Solvent Freezing |
Group I base oils are the least refined of all of the groups. They are usually a mix of different hydrocarbon chains with little or no uniformity. While some automotive oils on the market use Group I stocks, they are generally used in less demanding applications. |
| Group II |
Hydroprocessing and Refining |
Group II base oils are common in mineral-based motor oils currently available on the market. They have fair to good performance in lubricating properties such as volatility, oxidative stability and flash/fire points. They have only fair performance in areas such as pour point, cold crank viscosity and extreme pressure wear. |
| Group III |
Hydroprocessing and Refining |
Group III base oils are subjected to the highest level of mineral oil refining of the base oil groups. Although they are not chemically engineered, they offer good performance in a wide range of attributes as well as good molecular uniformity and stability. They are commonly mixed with additives and marketed as synthetic or semi-synthetic products. Group III base oil products have become more common in America during the past decade. |
| Group IV |
Chemical Reactions |
Group IV base oils are chemically engineered synthetic base stocks. Polyalphaolefins (PAOs) are a common example of a synthetic base stock. Synthetics, when combined with additives, offer excellent performance over a wide range of lubricating properties. They have very stable chemical compositions and highly uniform molecular chains. Group IV base oils are becoming more common in synthetic and synthetic-blend products for automotive and industrial applications. |
| Group V |
As Indicated |
Group V base oils are used primarily in the creation of oil additives. Esters and polyolesters are both common Group V base oils used in the formulation of oil additives. Group V oils exhibit a wide variety of properties specific to each individual oil's formulation. Group V base oils are generally not used as base oils themselves, but add beneficial properties to other base oils. |
