Lube Condition Indicators
Viscosity, Neutralization Number (TAN/TBN)
Like wear metals, these values have tolerances and it is very important to have new lubes base data on these parameters before attempting to diagnose changes and trends. PAL has a wealth of data in its files, but such data can become obsolete over extended time periods as oil companies find improved ways to meet particular specs and change their formulation for a product whose trade name remains the same. For this reason one should periodically have PAL test new incoming lube batches. Certainly not every time, but perhaps every six months. Change for the better is good - not knowing about it could be confusing!
Viscosity of a lubricant is its flow rate with respect to temperature. Two things are therefore necessary in reporting viscosity: temperature at which the viscosity is measured, and the amount of time units for a given amount of the lube to flow through a given passage.
The two most common temperatures for oil viscosity are 40 and l00° Centigrade. The units reported are Celtistokes, abbreviated "cSt". Viscosity was previously reported 100 and 210° F in units of SUS (Saybolt Universal Seconds). The change in viscosity temperatures and units is the result of an effort to standardize to a common world system; essentially it is metrication of the viscosity reporting system.
