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Viscosity is an important attribute of all lubicanting products. It is
a measure of the ability of oil to flow. The challenge of a lubricating
oil is to flow easily at engine start-up and thus provide immediate protection
for the moving parts. Conversely, the tendency of an oil to "thin-out"
at higher temperatures must be controlled to provide protection to the
moving parts as the engine reaches operating temperature.
Measurement of Viscosity
The viscosity of an oil is measured at a specifided temperature to determine
the ability of the oil to flow through a standard opening. There are four
major classifications of viscosity:
- ISO VG - measurement in centistokes (cSt) at 40 C
- AGMA - American Gear Manufactures Association
- SAE - Society of Automotive Engineers e.g. SAE30
- Saybolt - These units are in S.U.S an were used by various refiners
to specify viscosity at 100 F or 210 F
Please refer to the Viscosity Equivalents
Chart for a comparison of the classifications.
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