Cavitation in lubrication liquids has long been known to be detrimenta
l to components in hydraulic systems. Damage has been detected in jour
nal bearings, especially under severe dynamic loading, gears, squeeze
film dampers and valves.These findings have led to intensive studies o
f metal resistance to cavitation erosion, in order to minimize the dam
age. Results of these studies have been:(a) classification of known ma
terials according to their resistance to cavitation erosion; (b) devel
opment of new materials and processes to increase their durability. On
e of the main achievements in this respect was the establishment of th
e ASTM G32-92 Standard Method of Vibratory Cavitation Erosion Test. Ho
wever, very little was done with respect to the liquid phase, e.g. the
lubricants. As a consequence there is no standard procedure for testi
ng of lubricants for their cavitation properties and no relevant speci
fications in national and international standards. This study includes
theoretical and experimental investigations. The theoretical approach
examines the lubricant in elastohydrodynamically lubricated (EHL) con
tacts. Using numerical simulations, based on Reynolds equation and ela
stic deformation theory, the pressure profile and film shape have been
computed. It is further investigated how the operating conditions aff
ect the properties, e.g. ''cavitation energy'' of zones of sub-ambient
pressure values and if a correlation between these results and cavita
tion erosion criteria can be found. The experimental approach includes
testing of 20 liquid lubricants, belonging to the following four grou
ps: mineral oils, mineral-based oils, bio degradable oils and syntheti
c oils. Testing was performed by vibrating a standard aluminium tip in
each oil and periodically recording the gravimetric results. These re
sults enabled the classification of the lubricants according to their
cavitance, which is inversely proportional to the mass of solid materi
al eroded by a cavitating liquid under controlled conditions. The resu
lts of both approaches can be combined into an engineering tool in the
future. This tool may serve the designer to improve the use of existi
ng lubricants and the lubrication industry as an aid for the developme
nt of new lubricants with increased cavitance in hydraulic systems.