Why is base oil so important to a finished lubricant? Well, base oil is the primary component and establishes a “baseline” for overall performance. In fact, over 75% of a motor oil is base oil. The remaining 25% consists of additives that enhance or customize properties.
There are five recognized groups of base oil, categorized by the American Petroleum Institute (API). The varying groups provide differing levels of performance based on how the base oil is refined or synthesized.
Groups I, II and III are all refined from crude oil and are differentiated based on the severity of refining – enhanced severity removes impurities, providing better base oil performance. Group III can be marketed as a “synthetic” base oil due to its refining severity, while group IV (PAO: polyalphaolefin) is the original synthetic base oil. Group IV (PAO) base oils are chemically synthesized, meaning they are “built” from select molecules for improved performance. Group V is a “catch-all” group, used to formulate specialized oils, including esters, polyalkylene glycols, silcones and others.
Each API group is defined based on viscosity index (the higher the VI, the less change in viscosity with change in temperature), saturates (measures stable versus reactive molecules; better saturation means less oxidation) and sulfur content (sulfur is corrosive and can poison exhaust catalysts). As shown by the chart below, each step up in groups I-IV offers improved performance.
Base Oil Benefits
The most important qualities of higher-performing base oil include:
- Oxidation Resistance: prevents viscosity increase, deposits and acid formation
- Viscometrics: a higher VI base oil will be more stable across temperature changes
- Cold Weather Operability: better refining leads to less paraffin wax, providing improved cold flow; group IV base oil does not contain paraffin wax, offering exceptional cold flow
- Volatility: improved refining severity offers lower volatility (evaporation) which helps prevent increased oil consumption
The FS “Base” Slate
FS primarily markets lubricants blended with Group II, III and IV (PAO) base oil, reserving Group I for very few products. FS blends its motor oils, hydraulic fluids, transmission fluids and gear oils to outperform OEM and industry specs for longer lasting protection. Therefore, it is critical the foundation (the base) starts out at a higher performance level.
Curious to learn more? Contact your FS Energy Sales Specialist today.