What do Group I, II, and III mean, and what’s so great about Group II and Group III?
Groups I, II, and III are broad categories of base stocks developed by the American Petroleum Institute for the purpose of creating guidelines for licensing engine oils. Typically, solvent-refined base oils fall into Group I, while hydroprocessed base stocks fall into Group II. Unconventional Base Oils (UCBOs) or Very-High VI stocks are normally categorized as Group III. Group II+, though not an official API designation is a term used increasingly to describe Group II stocks of higher VI (110-119) and lower volatility than typical group II stocks. Group I oils contain high levels of sulfur and aromatics, which are compounds that can diminish performance. Group II & III oils have lower levels of these impurities, which result in enhanced oxidation performance for fully-formulated lubricants. Thanks to Chevron’s proprietary ISODEWAXING technology, Chevron’s Group II and III base oils have a unique low-wax composition, which delivers better low-temperature performance compared to many oth
