1. A method of condensation and polymerization in which a light mineral oil and fatty oil mixture is exposed to an electric discharge in a hydrogen atmosphere, yielding a viscous oil.
2. A process of condensation and polymerization in which a mixture of a relatively light mineral oil and a fatty oil is subjected to an electric discharge in an atmosphere of hydrogen.

The product is a very viscous oil (thick and sticky, reluctant to flow, and difficult to stir) used for blending with lighter lubricating oils.