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Since the 1990s, there has been increasingly higher demand placed on lubricants. These demands were driven by heightened environmental awareness as well as manufacturers’ requirements. Following the International Lubricants Standardization and Approval Committee (ILSAC) recommendation for the use of SAE 10W/30 viscosity grade engine oil, there was a trend towards the use of low-viscosity and low-emission lubricants. As the key raw material used in lubricants, lube base stocks should possess the following characteristics: low viscosity, low volatility, high viscosity index, and good oxidation stability to name a few. Broadly speaking, American Petroleum Institute’s (API) Group Ⅱ, Group Ⅲ and poly-alpha-olefin (PAO) synthetic oils possess these characteristics (unlike conventional solvent refined base oils). Group II and Group III lube base stocks are often suitable and highly economical substitutes for expensive synthetic base oils to produce premium multi-grade lubricants such as GF-1, GF-2, GF-3 and GF-4.

■ Typically, solvent extracted base stocks fall into Group I.
■ Hydrotreated base stocks and some lower quality hydrocracked base oils into Group II.
■ Hydrocracked base stocks are often categorized in Group III.
■ The Group IV base stock is poly-alpha-olefins (PAOs).
■ The Group V category contains synthetics other than PAOs, esters and naphthenics (with typical VIs lower than 80).

S-OIL’s aramcoULTRA series products (aramcoULTRA4/S6/S8) fall into the Group III category and exhibit superior physical properties and performance over Group I and Group II products.