Evaporation loss, GC

OELCHECK test instrument: Gaschromatograph Clarus 600 by PerkinElmer
Sample quantity: approx. 5 ml
Unit: amount in %
Test result: amount of oil which evaporates in 60 minutes from an oil sample of 65 grams at a temperature of 250 °C
Analysis for: engine oils, high-temperature oils
Brief description: Oil is broken down by heating into its constituent parts. The oil's constituents are separated in a separation column in order of increasing boiling temperature. After this, the percentage share of the components that evaporate at a temperature of 250 °C is determined from the total quantity of all of the components.
Statement: The evaporation loss can inform about the viscosity characteristics of an oil. For engine oils, fuel consumption usually increases with the viscosity. The lower the loss of oil due to evaporation, the lower the oil consumption and the more stable its viscosity characteristics. Consequently, the loss of fresh engine oil due to evaporation is another indicator of the engine oil's quality. The higher it is, the more oil is consumed.

Loss due to evaporation is a deciding factor for many other lubricants too, such as high-temperature chain oils.
Underlying test standard: DIN 51581-2