The value of friction and wear reduction in rapeseed oil modified with bio based additives was estimated by a four ball test machine examining lubricating materials. To improve the parameters the rapeseed oil was modified with oleic acid (1, 2 and 4%) and monodiglycerides (0,5%). Research results indicate that the increasing oleic acid concentration in rapeseed oil directly inreases the surface protection against wear and unambiguously affects the friction coefficient. Monodiglycerides improve wear reduction of lubricating material (rapeseed oil and oleic acid) and decrease the moment of friction. Rapeseed oil modified with these materials reduces the friction more effectively than commercial biological oils do.
