Oils

The most common type of fluid lubricant are different types of oils.

Mineral oil

This term is used to encompass lubricating base oil derived from crude oil. The American Petroleum Institute (API) designates several types of lubricant base oil identified as:

Group I – Saturates <90% and/or sulfur >0.03%, and Society of Automotive Engineers (SAE) viscosity index (VI) of 80 to 120
Manufactured by solvent extraction, solvent or catalytic dewaxing, and hydro-finishing processes. Common Group I base oil are 150SN (solvent neutral), 500SN, and 150BS (brightstok)


Group II – Saturates over 90% and sulfur under 0.03%, and SAE viscosity index of 80 to 120
Manufactured by hydrocracking and solvent or catalytic dewaxing processes. Group II base oil has superior anti-oxidation properties since virtually all hydrocarbon molecules are saturated. It has water-white color.

Group III – Saturates > 90%, sulfur <0.03%, and SAE viscosity index over 120
Manufactured by special processes such as isohydromerization. Can be manufactured from base oil or slax wax from dewaxing process.

Group IV – Polyalphaolefins (PAO)

Group V – All others not included above
 
 Synthetic Oils

There are many types of synthetic oils, but the most popular types of sythetic oils are:

Polyalpha-olefin (PAO)
Synthetic esters
Polyalkylene glycols (PAG)
Phosphate esters
Alkylated naphthalenes (AN)