TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Composition: The cycloalkane base oil comprising 20-40 wt.% isoparaffins. It comprises less than or equal to15 ppm sulfur. greater than or equal to70 (preferably 99) wt.% of the cycloalkanes comprises the alkyl-substituted cycloalkanes. The cycloalkane-base dielectric liquid comprises greater than or equal to60 (preferably 66) wt.% cycloalkanes. The dielectric liquid comprises less than or equal to5 (preferably 0.5-1) wt.% anti-gassing agent.Preferred Components: The cycloalkanes comprise alkyl-substituted cycloalkanes. The antigassing agents are alkyl-substituted aromatic compounds and/or alkyl substituted, partially saturated aromatic compounds, having from 9-11C carbon atoms; and a combination comprising 80 wt.% 1,5-dimethyl naphthalene and 20 wt.% isomeric dimethyl naphthalenes. The antigassing agents are dihydrophenanthrene, phenyl ortho xylyl ethane, alkylated benzenes, tetrahydro-5-(1-phenylethyl)naphthalene, acenaphthene, tetrahydronaphthalene, alkylated tetrahydronaphthalenes, or tetrahydroquinoline. The cycloalkane-base dielectric liquid further comprises antioxidant such as hindered phenols, cinnamate type phenolic esters, and alkylated diphenylamines; oxidation reducing antioxidant such as 2,6-ditertiary-butyl para-cresol, and/or 2,6-ditertiary butylphenol in an amount effective to reduce sludge formation and total acid number (TAN) under oxidation conditions.Preferred Parameters: The boiling is carried out at 260-371 degreesC. The cycloalkane base oil boils at 260-371degreesC. The anti-gassing agent(s) are effective to reduce the gassing tendency of the dielectric liquid to +30 (preferably +5) muL/min or less. The isomerization/dewaxing/hydrogenation (IDH) conditions comprise IDH temperatures of 250-390degreesC; IDH gas pressures greater than atmospheric; IDH hydrogen circulation rates of 400-15000 SCF/B; and, IDH liquid hourly space velocities of from about 0.1-20/hr. The refining conditions are effective to produce aromatic vacuum gas oil comprising the following distribution of carbonaceous materials, in descending order of concentration: aromatics greater than cycloalkanes greater than isoparaffins greater than normal paraffins. It produces aromatic vacuum gas oil comprising 40-60 (preferably 55-60) wt.% aromatic content, 20-30 wt.% cycloalkanes, 10-15 wt.% isoparaffins, and 5-15 wt.% normal paraffins.Preferred Method: The hydrocracking conditions comprise a hydrocracking pressure greater than atmospheric pressure and the stripping conditions comprise a stripping pressure greater than atmospheric pressure. The hydrotreating conditions comprise hydrotreating catalyst effective to convert unsaturated bonds into saturated bonds comprising converting at least some of any remaining aromatics into cycloalkanes; and, hydrotreating pressure of greater than atmospheric pressure. EXAMPLE - The inventive cycloalkane base oil was mixed with 0.075 wt.% butylated hydroxy toluene. Samples were prepared containing no added aromatic oil containing 2 wt.% 9-11C alkylbenzenes, 0.5 wt.% dimethylene naphthalenes. The resulting mixture was oxidized at 110degreesC in the presence of copper catalyst coil. The formed sample performed well exhibiting a negative gassing tendency.