Abstract: The invention comprises an apparatus for cleaning chambers such as those of engines and transmissions, including a reservoir, a quantity of synthetic cleaning fluid disposed in the reservoir, a first channel for fluidly connecting the reservoir with a first oil passageway opening in an internal combustion engine, a second channel for fluidly connecting the reservoir to a second oil passageway opening in the internal combustion engine, and a pump for pumping the synthetic cleaning fluid from the reservoir through the first channel and into the engine and then back to the reservoir through the second channel.