– Group II base oil is produced using a hydro-treating process to replace traditional solvent refining processes. Hydrogen gas is used to remove unwanted components from crude oil. Due to its low sulfur, nitrogen, and aromatic content, Group II base oil is transparent.
– Group II base oil has a hydrocarbon content of >90%, sulfur <0.03%, and a viscosity index between 80-120. Due to the ‘hydro’ treatment of hydrocarbon molecules, Group II oil has better oxidation resistance. Group II oil is more expensive than Group I oil.
– Group II base oil is commonly used to produce engine oil with SAE viscosity grades such as 10W-XX or 15W-XX; currently, it accounts for 85% of Diesel engine oil in Europe. The characteristics of this oil group include high dynamic viscosity suitable for formulating Heavy Duty Diesel Engine Oil, which requires high durability of the lubricating oil film between metal surfaces operating at high temperature and high shear rate (HTHS – High Temperature/High Shear) at low speeds but very high torque. This type of base oil is important due to its low sulfur and almost no aromatic compound content, resulting in stable oxidation and high thermal stability when blended with Low/Medium SAPS formulations.
– The common API standards for this oil are CI-4, CJ-4.