Abstract: A formulated composition is disclosed which is designed to clean baked-on, carbonized sludges and varnish deposits from the upper cylinder surfaces of automobile, motorcycle and truck engines. The product is comprised of a mutually synergistic solution of selected cyclic compounds, aliphatic amines and water, preferably dissolved in a hydrocarbon or hydrocarbon and aliphatic lower alcohol fuel base, to which minor materials may optionally be added. The solution or base product may be placed in a pressure resistant (aerosol) container pressurized with a compressed gas, such as nitrogen gas. A preferred embodiment of the invention utilizes a synergistic solution of N-methyl-2-pyrrolidone, n.butylamine and de-ionized water, with these ingredients present at certain ratios. This solution is dissolved in either mixed iso-(C.sub.7, C.sub.8)-hydrocarbons or a combination of such hydrocarbons with a minor amount of isopropanol, to which up to about 10% by weight of other optional ingredients may be added.