Thermophysical and viscosimetric properties of environmentally acceptable lubricants

Abstract

PurposeThe use of alternative oils for the lubrication of automobile engines has a potential of ecological and technical advantages. It requires the detailed knowledge of several thermophysical and viscosimetric properties in a large temperature range.Design/methodology/approachFor 11 different oils, the density, the heat capacity, the thermal conductivity, the viscosity at ambient pressure and the pressure‐viscosity at maximal 1,000 bar have been measured. The latter has been measured with a newly developed apparatus which is described in detail. Two hydrocarbon‐based factory‐fill oils and nine alternative oils have been tested. Five of the alternative oils are based partly or completely on esters, the other four on polyglycols, one of them additionally on water.FindingsData for thermophysical and viscosimetric properties are given in form of diagrams and tables. The consequences for the cooling capacity and the film forming behavior are discussed. The latter is only slightly better for the factory‐fill oils, compared to the alternative oils.Research limitations/implicationsThe pressure‐viscosity is measured at up to 1,000 bar, which is lower than the maximum pressure in the tribological contacts of an engine.Practical implicationsThe published data can be used to calculate tribological contacts which are lubricated with alternative engine oils or with actually used factory‐fill oils. This might help to decide if esters or polyglycols are superior as engine oils.Originality/valueThe results of this test program might be helpful for engineers who are interested in using alternative lubricants in tribosystems.