Scientific ideas on friction, lubrication and wear of solids are presented. Modern provisions describing the physical essence of these processes both in machine parts and in the main interfaces of piston engines - cylinder-piston group and crank mechanism are considered. Described is a methodology for rational design and selection of materials for the main friction parts of piston engines, aimed at minimizing their friction and wear. Analysis of typical and non-standard methods of piston engine tribometry and examples of performed resource-saving technical solutions are given.