Naphthenic oil is a type of mineral oil. In contrast with paraffinic oils, naphthenic oils contain only low to no proportion of n-alkanes, being based on cycloalkanes (naphthenes) instead. The low-temperature behavior of naphthenic oils is better than of paraffinic oils, making them suitable for applications that require low pour point. The degradation products of naphthenic oils are soluble in the oils, leading to fewer problems with formations of sludges and deposits. Naphthenic oils have different solvent properties than paraffinic oils.

Naphthenic oils are characterized by high proportion of cyclic hydrocarbon fraction. The convention is that when the paraffinic carbon content is less than 55-60%, the oil is labeled as naphthenic.[1]

The principal uses of naphthenic oils are as transformer oils, coolants, solvents, cutting fluids, and some lubricants.

See also