The feasibility of use of motor oils in engines as the base of flushing products is explored. A technological process is proposed for cleaning working dirty motor oil without draining it out from the engine crankcase and subsequent addition to it of agents that facilitate removal of deposits from the cylinder-piston group parts. It is shown that resin and asphaltene particles can be enlarged by using monoethanolamine and isopropanol as agents to sizes that are easily removable by cleaning agents integrated into the engine lubrication system. It is determined that subsequent addition of dimethyl sulfoxide blended with white spirit to cleaned motor oil used in the engine makes it possible to remove resins and tars from engine parts, raise compression, and reduce fuel consumption.