Operating viscosity


The viscosity of a fluid is its resistance to flow and is highly influenced by temperature. It decreases with rising temperature, i.e. the fluid becomes more liquid. However, the change is not linear to temperature, but shows a double-logarithmic relationship. This relationship, which was described by Ubbelohde and Walther, refers to mineral oils and, in the first approximation, can also be used for synthetic oils.

Operating viscosity of lubricants

The operating viscosity for oils and bases oil of lubricating greases from Klüber Lubrication can be determined approximately by means of the known kinematic viscosity at 40 °C and 100 °C.  The viscosity of a lubricant (taking into account loads, speed, etc.) is one of the indicators for lube film formation protecting against friction and wear. Synthetic oils, special additives and various thickener concepts enable the lubricating film to be formed already at a lower, energy-efficient viscosity 

Operating viscosity and temperature

Kinematic base oil viscosity
  • All fields are mandatory
  • V 40°C must be bigger than V 100°C
  • V 100°C must be bigger than 2 mm²/s
  • V 40°C and V 100°C can not be 0
The calculations on this website are based on general experience and knowledge acc. to DIN 51563 and Ubbelohde-Walther at the time of publication and are for information only. The results are approximate values for predicting the operating viscosity. In practice, however, the actual viscosity value has to be checked by the user by means of suitable methods in each individual case. The information does not constitute any statement as to specifications, assurance of properties/warranties or the suitability of products for specific applications. All information is subject to change and does not claim to be exhaustive, correct or accurate. Klüber products are continually improved. Therefore, Klüber Lubrication reserves the right to change all the technical data at any time without notice.