A cheap noninflammable solvent is desired for cleaning engine parts. Carbon tetrachloride is noninflammable, but its market price per gallon is five or six times that of gasoline. Mixtures of gasoline and carbon tetrachloride have been used as a cleaning fluid. However, about one-third gasoline is about the maximum proportion that can be used to obtain a nonburning fluid. This fluid would cost about four times as much as gasoline or one-quarter less than the carbon tetrachloride alone. The fire risk as compared with gasoline and clost as compared with two-thirds carbon tetrachloride are greatly decreased if the cleaning fluid is made slow burning rather than noninflammable. The tests covered in this report were made to determine the feasibility of this type of cleaning fluid. Since engines treated for storage are not readily cleaned by gasoline alone, but are being cleaned at present by a fluid consisting of equal proportions of alcohol and benzol, this fluid was included in these tests. The objects of these tests is to determine the minimum proportions of carbon tetrachloride required to produce a sufficiently slow-burning cleaning fluid for safe use in cleaning engines.