Viscosity measurement at 100 degrees is used to assess lubricity at high operating temperatures, such as in internal combustion engines and turbines. It complements the measurement at 40℃ and is often used to calculate viscosity index.
The method is similar to that at lower temperatures, but here it is high heat that reveals how stable the oil is under demanding conditions.
Deviations from the expected value may indicate degradation, thinning or contamination. The customer gets a clear picture of whether the oil is still functioning optimally in hot environments.