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Pour Point
Specific Gravity
Thermal Expansion
Bulk Modulus
Gases in Mineral Oil
Vapor Pressure
Flash Point
Thermal Conductivity
Specifice Heat
Electrical Conductivity
Surface Tension
Base Oil
  Thermal Conductivity  

Thermal conductivity is the rate of transfer of heat for a given temperature gradient through a material. The rate of transfer of heat from a hot spot to a cooler area in a bearing is a factor in controlling overheating. Therefore, an oil with a high thermal conductivity would be expected to lower the temperature of a bearing. Thermal conductivity of a lubricating oil is used in equations to calculate heat transfer in bearings. The unit of thermal conductivity is heat over a distance per degree of temperature. Most mineral oils have approximately the same thermal conductivity of near 0.1 W m-1 degree C-1. (For reference, the thermal conductivity of water and ethylene glycol are about 3 times higher than oils ).

Thermal conductivity is measured using ASTM D 2717. This method consists of a test vessel containing oil and a platinum resistance thermocouple. Thermal conductivity is determined by measuring the temperature gradient produced across the liquid sample by a known amount of heat introduced into the cell by an electrically heated platinum element. Thermal conductivity increases slightly with higher temperatures.