NOVELTY - A cycloalkane base oil comprises isoparaffins and 50-70 wt.% cycloalkanes. The quantity of isoparaffins is less than 50 wt. % of the cycloalkane base oil.    USE - For use in producing cycloalkane-base dielectric liquids (claimed).    ADVANTAGE - The inventive base oil provides cycloalkane-base dielectric liquid that meets the chemical property requirements for electrical oils. The sulfur content is low, thus preventing corrosion of certain metals such as copper and silver in contact with the dielectric liquid. The invention includes anti-gassing agent that is effective to reduce the gassing tendency of the dielectric liquid.    DETAILED DESCRIPTION - A cycloalkane base oil comprises isoparaffins and 50-70 wt.% cycloalkanes having the formula CnH2n, where n is 15-30, the quantity of isoparaffins being less than 50 wt. % of the cycloalkane base oil.    INDEPENDENT CLAIMS are also included for:    (A) a cycloalkane-base dielectric liquid, comprising the inventive cycloalkane base oil, and non-phenolic alkyl substituted or partially saturated aromatic anti-gassing agent comprising labile hydrogen atom, where the quantity is effective to reduce the gassing tendency of the dielectric liquid; and    (B) a method for making a cycloalkane base oil, comprising refining crude under refining conditions effective to produce aromatic vacuum gas oil boiling at 371-538degreesC, the aromatic vacuum gas oil comprising carbonaceous materials, a majority of the carbonaceous materials such as cycloalkanes and aromatics; contacting the aromatic vacuum gas oil with hydrocracking catalyst under hydrocracking conditions effective to produce hydrocracking product; subjecting hydrocracking product to stripping conditions effective to increase the content of cyclic hydrocarbons selected from the group consisting of cycloalkanes, and/or cycloalkenes, and removing hydrogen sulfide and ammonia and producing stripped hydrocracking product; contacting stripped hydrocracking product with isomerization/dewaxing/hydrogenation (IDH) catalyst comprising a metal such as platinum and/or palladium, under IDH conditions effective to saturate aromatics to cycloalkanes, reduce normal paraffins, and to produce IDH product comprising greater than 50 wt.% of cyclic hydrocarbons such as cycloalkanes or cycloalkenes; without solvent extracting, contacting IDH product with hydrotreating catalyst under hydrotreating conditions effective to produce hydrotreated product comprising greater than 50 wt.% cycloalkanes; and, separating from the hydrotreated product cycloalkane base oil comprising less than 50 wt.% isoparaffins and greater than or equal to50 wt.% cycloalkanes base oil boiling, at 260-371degreesC.